To begin, it makes sense to give a brief overview of Scripture's teaching on the death penalty.
Before the Law of Moses, God imposed on all of mankind that the death penalty should be carried out for the crime of murder:
Genesis 9:5-6
5 And surely your blood of your lives will I require; at the hand of every beast will I require it, and at the hand of man; at the hand of every man's brother will I require the life of man.
6 Whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man.
Notice that God gives the basis for the punishment - the fact that the very image of God has been violated by the murderer. This is a basis rooted in the very essence of our human nature, and the justice that the most obscene violation of the image of God requires.
Under the Mosaic Law, the command to execute murderers was reiterated repeatedly (Exodus 21:12-14, Leviticus 24:17, 24:21, Numbers 35:16-21, 35:30-34, Deuteronomy 19:11-13), along with commands to execute people for many other offences (Exodus 21:15-17, 22:20, Leviticus 20:2, 20:9-16, Deuteronomy 18:20, 22:25, etc.).
Further, in the Bible, it is explicitly said that if murder is not punished with the death penalty, then the innocent blood has not been properly avenged, and therefore the entire land is regarded as guilty. This is seen in some of the passages referenced above, and also in the New Testament, when the martyred saints are asking God to apply the exact same principle:
Numbers 35:30-33
30 Whoso killeth any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.
31 Moreover ye shall take no satisfaction for the life of a murderer, which is guilty of death: but he shall be surely put to death.
32 And ye shall take no satisfaction for him that is fled to the city of his refuge, that he should come again to dwell in the land, until the death of the priest.
33 So ye shall not pollute the land wherein ye are: for blood it defileth the land: and the land cannot be cleansed of the blood that is shed therein, but by the blood of him that shed it.
Revelation 6:9-10
9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:
10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
The principle of a land being reckoned as guilty before God when innocent blood is not avenged by capital punishment is also seen in Deuteronomy 19:11-13, and even when the perpetrator couldn't be found, God required a ritual to cleanse the guilt of the innocent blood (Deuteronomy 21:1-9).
Therefore, the Bible is unequivocal in - not merely allowing, or recommending - but mandating the death penalty, especially in the case of murder, even before the Old Testament. It is a punishment rooted in the fundamental fact that humans are made in the image of God, and that the heinous violation of the image of God requires justice, in order for the entire land not to be reckoned as guilty before the Lord.
And, lest any human being think that they can ever improve upon the Law given directly by God himself, it should be emphasized that the Law that God gave is utterly perfect in every way, and the ideal form of justice in regard to determining penalties for moral offenses - which are still moral offenses under the New Covenant:
Psalm 19:7
7 The law of the LORD is perfect, converting the soul: the testimony of the LORD is sure, making wise the simple.
The death penalty - especially in the case of murder - is not an Old Testament vs New Testament issue. Rather, it is a timeless principle of justice, given by the God who always judges justly.
For most of its history, the Catholic Church agreed precisely with the perspective presented in the section above.
For example, Pope Innocent I (360-417 AD) wrote the following on the topic:
Pope Innocent I - Ad Exsuperium, Episcopum Tolosanum (405 AD)
It must be remembered that power was granted by God, and to avenge crime the sword was permitted; he who carries out this vengeance is God's minister [Romans 13:1–4]. What motive have we for condemning a practice that all hold to be permitted by God? We uphold, therefore, what has been observed until now, in order not to alter the discipline and so that we may not appear to act contrary to God's authority.
Notice that the above is an apologetic for the death penalty, based on Romans 13:1-6, which together with 1 Peter 2:13-15 tells us that government's primary role is to punish evildoers, and when they do so, they are doing the will of God. The Apostle Paul even personally affirmed this role in his own experience, when it was his life on the line, in Acts 25:11.
Next, in the Catechism published under Pope Pius V (1504-1572 AD) following the Council of Trent (1545-1563 AD), we read:
The Catechism of the Council of Trent (1566 AD) - Execution Of Criminals
Another kind of lawful slaying belongs to the civil authorities, to whom is entrusted power of life and death, by the legal and judicious exercise of which they punish the guilty and protect the innocent. The just use of this power, far from involving the crime of murder, is an act of paramount obedience to this Commandment which prohibits murder.
The end of the Commandment is the preservation and security of human life. Now the punishments inflicted by the civil authority, which is the legitimate avenger of crime, naturally tend to this end, since they give security to life by repressing outrage and violence. Hence these words of David: In the morning I put to death all the wicked of the land, that I might cut off all the workers of iniquity from the city of the Lord.
Notice especially that once again, the above is not a simple statement of permissibility. Rather, it's a defence of the use of the death penalty, on the basis of the Biblical principles of justice involved. It says that it is "an act of paramount obedience to this Commandment which prohibits murder" - that is, executing criminals follows a commandment, therefore, it is rightly described as an obligation - not merely an option.
This sentiment is reiterated in the Catechism published under Pope Pius X (1835-1914 AD):
The Catechism of St. Pius X (1908 AD) - The Fifth Commandment
3 Are there cases in which it is lawful to kill?
It is lawful to kill when fighting in a just war; when carrying out by order of the Supreme Authority a sentence of death in punishment of a crime; and, finally, in cases of necessary and lawful defence of one's own life against an unjust aggressor.
Not only has the Catholic Church historically supported the use of the death penalty, and argued for its justness, but it also has ensured the death penalty for many of those who disagreed with it on doctrinal matters - two famous examples, among thousands, being Jan Hus, who was burned at the stake in 1415 AD after being condemned by the Council of Constance (1414-1418 AD), and William Tyndale, killed in 1536 AD for being a heretic.
The burning of Jan Hus, and others like him, was defended during the time of Martin Luther, in Pope Leo X's (1475-1521 AD) list of errors:
Pope Leo X - Exsurge Domine (1520 AD)
33 That heretics be burned is against the will of the Spirit. (Condemned)
Above, Pope Leo X is denying the charge that burning heretics at the stake is against the will of the Holy Spirit.
Another instance of a "Vicar of Christ" showing approbation for the death penalty can be seen in Pope Pius V (1504-1572 AD), where in a Papal Bull addressing sodomy, he explicitly mandated the death penalty for offenders:
Pope Pius V - Horrendum Illud Scelus (1568 AD)
3 Therefore, wishing to pursue with greater rigor than we have exerted since the beginning of our pontificate, we establish that any priest or member of the clergy, either secular or regular, who commits such an execrable crime, by force of the present law be deprived of every clerical privilege, of every post, dignity and ecclesiastical benefice, and having been degraded by an ecclesiastical judge, let him be immediately delivered to the secular authority to be put to death, as mandated by law as the fitting punishment for laymen who have sunk into this abyss.
Another obvious example of Catholic support for the death penalty can be seen in the life of Giovanni Battista Bugatti (1779–1869 AD), who famously served as executioner for the Papal States for 68 years, and personally executed 514 criminals, before being retired by Pope Pius IX (1792-1878 AD).
Therefore, the Catholic Church, historically, has been in favor of the death penalty, and often worked closely with secular authorities to criminalize heretics, many of whom would then be remanded to secular courts, and executed (see Ad Extirpanda [1252 AD], etc.).
The Papacy of John Paul II (1920-2005 AD) marks the first major shift in the Church's teaching on the death penalty.
It was under his Pontificate, spurred by his encyclical Evangelium Vitae (1995 AD), that the Catechism was updated to read as follows:
Catechism of the Catholic Church 2267 (1997 AD)
2267 Assuming that the guilty party's identity and responsibility have been fully determined, the traditional teaching of the Church does not exclude recourse to the death penalty, if this is the only possible way of effectively defending human lives against the unjust aggressor.
If, however, non-lethal means are sufficient to defend and protect people's safety from the aggressor, authority will limit itself to such means, as these are more in keeping with the concrete conditions of the common good and more in conformity with the dignity of the human person.
Today, in fact, as a consequence of the possibilities which the state has for effectively preventing crime, by rendering one who has committed an offense incapable of doing harm - without definitively taking away from him the possibility of redeeming himself - the cases in which the execution of the offender is an absolute necessity" are very rare, if not practically non-existent."
Above, the death penalty is acknowledged as "the traditional teaching of the Church", and there is still allowance for it - but barely. It stops just short of condemning it, and extols non-lethal means as being "more in keeping with the concrete conditions of the common good and more in conformity with the dignity of the human person".
The next Pope, Benedict XVI (1927-2022 AD), would then openly declare the need for the death penalty to be abolished:
Pope Benedict XVI - Africae Munus (2011 AD)
83 Together with the Synod members, I draw the attention of society’s leaders to the need to make every effort to eliminate the death penalty and to reform the penal system in a way that ensures respect for the prisoners’ human dignity. Pastoral workers have the task of studying and recommending restorative justice as a means and a process for promoting reconciliation, justice and peace, and the return of victims and offenders to the community.
Once again, the "human dignity" of the offender is implied to be under assault by the institution of the death penalty. On that basis, he is rejecting it, and urging "every effort" to eliminate it.
Finally, Pope Francis gave a speech in October of 2017 in which he called the death penalty "an inhumane measure that, regardless of how it is carried out, abases human dignity", and stated that "it is per se contrary to the Gospel", and an "extreme and inhumane remedy that ignored the primacy of mercy over justice".
Consequently, on August 2, 2018 Pope Francis had the Catechism modified to read:
Catechism of the Catholic Church 2267
2267 Recourse to the death penalty on the part of legitimate authority, following a fair trial, was long considered an appropriate response to the gravity of certain crimes and an acceptable, albeit extreme, means of safeguarding the common good.
Today, however, there is an increasing awareness that the dignity of the person is not lost even after the commission of very serious crimes. In addition, a new understanding has emerged of the significance of penal sanctions imposed by the state. Lastly, more effective systems of detention have been developed, which ensure the due protection of citizens but, at the same time, do not definitively deprive the guilty of the possibility of redemption.
Consequently, the Church teaches, in the light of the Gospel, that “the death penalty is inadmissible because it is an attack on the inviolability and dignity of the person”, and she works with determination for its abolition worldwide.
This was re-affirmed later in Pope Francis's Encyclical entitled Fratelli Tutti:
Pope Francis - Fratelli Tutti (2020 AD)
263 There is yet another way to eliminate others, one aimed not at countries but at individuals. It is the death penalty. Saint John Paul II stated clearly and firmly that the death penalty is inadequate from a moral standpoint and no longer necessary from that of penal justice. There can be no stepping back from this position. Today we state clearly that “the death penalty is inadmissible” and the Church is firmly committed to calling for its abolition worldwide.
268 All Christians and people of good will are today called to work not only for the abolition of the death penalty, legal or illegal, in all its forms, but also to work for the improvement of prison conditions, out of respect for the human dignity of persons deprived of their freedom. I would link this to life imprisonment... A life sentence is a secret death penalty”.
Notice here that the Pope is speaking on behalf of the Church - "the Church is firmly committed to calling for its abolition worldwide". It is not merely his opinion, but a reflection of the Magisterium, which in Catholic theology, is infallible.
For a final example - though more could be cited, see Appendix I - in a scripted video uploaded to the Vatican's official PopeVideo YouTube channel, entitled "For the abolition of the death penalty", Pope Francis stated:
For the abolition of the death penalty (2022 AD)
Capital punishment offers no justice to victims, but rather encourages revenge. And it prevents any possibility of undoing a miscarriage of justice. Additionally, the death penalty is morally inadmissible, for it destroys the most important gift we have received: life.
And in light of the Gospel, the death penalty is unacceptable. The commandment "Thou shall not kill", refers to both the innocent and guilty. I, therefore, call on all people of goodwill to mobilize for the abolition of the death penalty throughout the world. Let us pray that the death penalty, which attacks the dignity of the human person, may be legally abolished in every country.
Thus, carrying out the death penalty is now officially a sin. Something that was once commended, commanded, and defended by the Roman Catholic Church, on the basis of Scripture, and universal acceptance, and tradition, is now something inherently sinful - "per se contrary to the Gospel".
There are a number of severe problems with this modification:
He has just contradicted not only the Bible, but the whole history of his own Church, as covered in the preceding section. This is not a "development". It's declaring sinful something that used to be endorsed. It is a contradictory change in the historical doctrine of the Church.
The Bible teaches the validity and requirement of the death penalty in certain circumstances, based on immutable principles of divine justice in creation. The Catholic Church, in the past, utilized the death penalty on those who disagreed with it on doctrinal matters, and declared its support for the death penalty constantly, and on the basis of Biblical principles.
Now, the Catholic Church not only contradicts the Bible's timeless, infallible teaching on the death penalty, but also contradicts the centuries-long, unambiguous affirmation of the death penalty given by its own Popes and councils. In 2018, the Church has overthrown a law given to Noah in Genesis chapter 9, over 4,000 years after it was given, and which it previously upheld, practiced, and defended.
This is one of many ways that prove to any impartial observer that the doctrine of Ecclesiastical and Papal infallibility can only be maintained by those who are ignorant of history, or so dedicated to suppressing the truth, as a result of the traditions that they have married themselves to, that they become past the point of reason.
Pope Francis - Address to the International Association of Penal Law (October 23, 2014)
All Christians and men of good will are thus called today to fight not only for the abolition of the death penalty, whether legal or illegal, and in all its forms, but also in order to improve prison conditions, with respect for the human dignity of the people deprived of their freedom. And I link this to life imprisonment. Recently the life sentence was taken out of the Vatican’s Criminal Code. A life sentence is just a death penalty in disguise.
Pope Francis - Message to the 6th World Congress Against the Death Penalty (June 21, 2016)
One sign of hope is that public opinion is manifesting a growing opposition to the death penalty, even as a means of legitimate social defense. Indeed, nowadays the death penalty is unacceptable, however grave the crime of the convicted person. It is an offence to the inviolability of life and to the dignity of the human person; it likewise contradicts God’s plan for individuals and society, and his merciful justice. Nor is it consonant with any just purpose of punishment. It does not render justice to victims, but instead fosters vengeance. The commandment “Thou shalt not kill” has absolute value and applies both to the innocent and to the guilty.
Today I would encourage all to work not only for the abolition of the death penalty, but also for the improvement of prison conditions, so that they fully respect the human dignity of those incarcerated. “Rendering justice” does not mean seeking punishment for its own sake, but ensuring that the basic purpose of all punishment is the rehabilitation of the offender. The question must be dealt with within the larger framework of a system of penal justice open to the possibility of the guilty party’s reinsertion in society. There is no fitting punishment without hope! Punishment for its own sake, without room for hope, is a form of torture, not of punishment.
Pope Francis - Address to the Pontifical Council (October 11, 2017)
Along these same lines, I would like now to bring up a subject that ought to find in the Catechism of the Catholic Church a more adequate and coherent treatment in the light of these expressed aims. I am speaking of the death penalty. This issue cannot be reduced to a mere résumé of traditional teaching without taking into account not only the doctrine as it has developed in the teaching of recent Popes, but also the change in the awareness of the Christian people which rejects an attitude of complacency before a punishment deeply injurious of human dignity. It must be clearly stated that the death penalty is an inhumane measure that, regardless of how it is carried out, abases human dignity. It is per se contrary to the Gospel, because it entails the willful suppression of a human life that never ceases to be sacred in the eyes of its Creator and of which – ultimately – only God is the true judge and guarantor. No man, “not even a murderer, loses his personal dignity” (Letter to the President of the International Commission against the Death Penalty, 20 March 2015), because God is a Father who always awaits the return of his children who, knowing that they have made mistakes, ask for forgiveness and begin a new life. No one ought to be deprived not only of life, but also of the chance for a moral and existential redemption that in turn can benefit the community.
In past centuries, when means of defence were scarce and society had yet to develop and mature as it has, recourse to the death penalty appeared to be the logical consequence of the correct application of justice. Sadly, even in the Papal States recourse was had to this extreme and inhumane remedy that ignored the primacy of mercy over justice. Let us take responsibility for the past and recognize that the imposition of the death penalty was dictated by a mentality more legalistic than Christian. Concern for preserving power and material wealth led to an over-estimation of the value of the law and prevented a deeper understanding of the Gospel. Nowadays, however, were we to remain neutral before the new demands of upholding personal dignity, we would be even more guilty.
Here we are not in any way contradicting past teaching, for the defence of the dignity of human life from the first moment of conception to natural death has been taught by the Church consistently and authoritatively. Yet the harmonious development of doctrine demands that we cease to defend arguments that now appear clearly contrary to the new understanding of Christian truth. Indeed, as Saint Vincent of Lérins pointed out, “Some may say: Shall there be no progress of religion in Christ’s Church? Certainly; all possible progress. For who is there, so envious of men, so full of hatred to God, who would seek to forbid it?” (Commonitorium, 23.1; PL 50). It is necessary, therefore, to reaffirm that no matter how serious the crime that has been committed, the death penalty is inadmissible because it is an attack on the inviolability and the dignity of the person.
Pope Francis - Mass of the Lord's Supper Homily (March 29, 2018)
This is your job: to help sow the hope of reintegration, and this will do everyone good. Always. Every sentence must be open to the horizon hope. This is why the death penalty is neither humane nor Christian. Every sentence must be open to hope, to reintegration, also to offer the experience for the good of other people.
Pope Francis - Address to the International Commission Against the Death Penalty (December 17, 2018)
The revision of the text of the Catechism in the article dedicated to the death penalty does not imply any contradiction with past teaching, because the Church has always defended the dignity of human life. However, the harmonious development of doctrine necessarily requires that the Catechism reflect the fact that, despite the gravity of the crime committed, the Church teaches, in the light of the Gospel, that the death penalty is always inadmissible because it offends the inviolability and dignity of the person.
Pope Francis - Address to the Diplomatic Corps (January 9, 2023)
The right to life is also threatened in those places where the death penalty continues to be imposed, as is the case in these days in Iran, following the recent demonstrations demanding greater respect for the dignity of women. The death penalty cannot be employed for a purported State justice, since it does not constitute a deterrent nor render justice to victims, but only fuels the thirst for vengeance. I appeal, then, for an end to the death penalty, which is always inadmissible since it attacks the inviolability and the dignity of the person, in the legislation of all the countries of the world. We cannot overlook the fact that, up until his or her very last moment, a person can repent and change.
Dignitas Infinita (April 8, 2024)
1 From this truth, the Church draws the reasons for her commitment to the weak and those less endowed with power, always insisting on “the primacy of the human person and the defense of his or her dignity beyond every circumstance.”
34 In addressing some of the many grave violations of human dignity today, we can draw upon the teachings of the Second Vatican Council, which emphasized that “all offenses against life itself, such as murder, genocide, abortion, euthanasia, and willful suicide” must be recognized as contrary to human dignity. Furthermore, the Council affirmed that “all violations of the integrity of the human person, such as mutilation, physical and mental torture, undue psychological pressures,” also infringe upon our dignity. Finally, it denounced “all offenses against human dignity, such as subhuman living conditions, arbitrary imprisonment, deportation, slavery, prostitution, the selling of women and children, degrading working conditions where individuals are treated as mere tools for profit rather than free and responsible persons.” Here, one should also mention the death penalty, for this also violates the inalienable dignity of every person, regardless of the circumstances. In this regard, we must recognize that “the firm rejection of the death penalty shows to what extent it is possible to recognize the inalienable dignity of every human being and to accept that he or she has a place in this universe. If I do not deny that dignity to the worst of criminals, I will not deny it to anyone. I will give everyone the possibility of sharing this planet with me, despite all our differences.” It is also fitting to reaffirm the dignity of those who are incarcerated, who often must live in undignified conditions. Finally, it should be stated that - even if someone has been guilty of serious crimes - the practice of torture completely contradicts the dignity that is proper to every human being.
Pope Francis - Spes Non Confundit (2024 AD)
10 In every part of the world, believers, and their Pastors in particular, should be one in demanding dignified conditions for those in prison, respect for their human rights and above all the abolition of the death penalty, a provision at odds with Christian faith and one that eliminates all hope of forgiveness and rehabilitation.
It should be noted that because of the frequent repetition of this doctrine, it easily meets the requirements for infallibility outlined by Vatican 2:
Vatican 2 (1965 AD) - Lumen Gentium
25 This religious submission of mind and will must be shown in a special way to the authentic magisterium of the Roman Pontiff, even when he is not speaking ex cathedra; that is, it must be shown in such a way that his supreme magisterium is acknowledged with reverence, the judgments made by him are sincerely adhered to, according to his manifest mind and will. His mind and will in the matter may be known either from the character of the documents, from his frequent repetition of the same doctrine, or from his manner of speaking.