Many maintain that Christians are saved by faith alone, but insist that one also must "call upon the name of the Lord" in order to accept the gift of Salvation. Therefore, they mandate that a new convert must ask for Salvation via a sinner's prayer.
The main proof text for this doctrine is found in Romans chapter 10:
Romans 10:9-10, 13
9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
13 For whosoever shall call upon the name of the Lord shall be saved.
Firstly, as with any supposed requirement being added to faith in order to be saved, if this means one has to pray or confess to be saved from Hell, we would expect to see it frequently alongside other passages that mention Salvation, and faith in Christ.
For example:
Acts 16:30-31
30 And brought them out, and said, Sirs, what must I do to be saved?
31 And they said, Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house.
There is no mention of prayer or confession in the above passage. Neither is there a mention of prayer or confession in John 3:16, 18, 36, 5:24, 6:47, Ephesians 2:8-9, Romans 4:5, 5:1, 10:4, etc. This means that if confession is required for Salvation from Hell, God told us one time, in the middle of the book of Romans, and left that out of dozens of other passages of Scripture which explain what we need to do to be saved.
Secondly, the proof text for this doctrine actually refutes it. Notice the bolded portion of the verse:
Romans 10:10
10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
According to verse 10, people are made righteous when they believe, which is consistent with the rest of the Bible's teaching on Salvation. If they are righteous at that moment, then confession is not required to be made righteous, because faith and confession are not synonymous.
So, what is the passage in question referring to, if not Salvation from Hell?
The word "saved" in Romans 10 is referring to salvation from temporal judgement or peril here on this earth, in a similar way that James 2:14 uses the word "save". The word "saved" or "salvation" refers many times in Scripture to temporal salvation (Matthew 8:25, 14:30, Romans 13:11, Philippians 1:19: 1 Timothy 2:15, 4:16: 1 Peter 3:20: 2 Corinthians 1:6, Acts 27:31, etc.).
Romans 10:13 is a direct quote from Joel chapter 2 (also quoted in Acts 2:20-21), which in context is all about deliverance from physical peril, specifically during the wrath of God on mankind following the Great Tribulation (compare Joel 2:31 with Revelation 6:12-17, Matthew 24:29):
Joel 2:32
32 And it shall come to pass, that whosoever shall call on the name of the Lord shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the Lord hath said, and in the remnant whom the Lord shall call.
The concept of "Calling upon the Lord" for salvation from temporal judgement or peril is clearly manifest elsewhere in Scripture:
Psalm 18:3 (2 Samuel 22:4)
3 I will call upon the Lord, who is worthy to be praised: so shall I be saved from mine enemies.
Psalm 50:15
15 And call upon me in the day of trouble: I will deliver thee, and thou shalt glorify me.
Psalm 55:16-18
16 As for me, I will call upon God; and the Lord shall save me.
17 Evening, and morning, and at noon, will I pray, and cry aloud: and he shall hear my voice.
18 He hath delivered my soul in peace from the battle that was against me: for there were many with me.
Also see Psalm 20:9, 80:18-19, 86:5, 86:7, 88:9, 91:15, 105:1, 116:2-4, 116:12-14, 118:5, 145:18-19. Turning this "Calling upon the name of the Lord" into a sinner's prayer to ask for Salvation from Hell requires mishandling of these texts, and ignorance as to how the phrase is used elsewhere in Scripture.
The context is the Apostle Paul's desire for the Jews to be saved (Romans 10:1). Because they, as a nation, had rejected the Messiah, Paul knew that they were due for judgement as a nation, here on this earth. But, his statement in verse 14 makes it clear that in order for them to confess Jesus, whether as a nation or individually, they must first believe:
Romans 10:14
14 How then shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher?
The Apostle Paul says that they cannot call upon/confess Jesus if they have not believed. They have to believe first. And since people are saved as soon as they believe, these people would already be saved - from Hell. They are not saved in the sense that Paul is speaking of here, in regard to temporal judgement, until they call upon Him/publicly confess Him as the Messiah.
The Apostle Paul is saying that unless the Jews as a group turn to open confession that Jesus was the Messiah, they will not saved from the wrath of God as a nation - here on this earth. Obviously, in order to do so, they must first believe. Otherwise, the Jewish nation as a whole would suffer judgement, which came to pass during the Roman re-conquest of the Jewish nation during the First Jewish-Roman War (66-74 AD).
It was during this war that Jerusalem was sacked and the Temple was obliterated, which was a clear sign of God's wrath for having rejected the Messiah. This is what Paul is warning them of here. Unless as a people they made it known that they accepted Jesus as the Messiah, and called upon Him for mercy, they would not be saved from this judgement.
As believers, confession is our recourse to temporal forgiveness for our sins (1 John 1:9). This has to do with our fellowship with God, not our eternal standing. Eternally speaking, all of our sins, past, present, and future, are already washed away forever (Revelation 1:5), hence why no believer can ever face eternal condemnation (John 5:24). However, believers can certainly face the temporal condemnation which is being referred to in Romans 10 (1 Corinthians 11:30-32, Hebrews 12:6, Revelation 3:19).
The false doctrine that one must, in addition to believing in Jesus, pray a prayer in order to get Eternal Life, stems from a misunderstanding of how the word "saved" is used in Scripture. It is a confusing, unbiblical addition to the Gospel message.