Mark 16:16
16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
This verse is commonly used to teach Baptismal Regeneration - that one must be water baptized to be born again.
Notice that belief is on both sides of the dichotomy in Mark 16:16, whereas baptism is only on the first side. This would only teach baptismal regeneration if baptism were on both sides of the dichotomy alone, or on the second side alone.
It's true that if someone believes and is baptized they will be saved, because if someone believes and does anything else they are saved, as the essential part is belief - which we can see from other dichotomies in Scripture:
John 3:18
18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
John 3:36
36 He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.
This is why belief is mentioned alone on the second side of Mark 16:16. If someone believes they are "not condemned", "have Everlasting Life", and from our verse in question, "shall be saved". If they don't, they are "condemned already", they "shall be damned", and they "shall not see life, but the wrath of God abideth on him".
In this view, baptism is only called out by the Lord because it is the first step of obedience following faith in Jesus Christ (Acts 8:35-38), and the intended beginning of the Christian life as a public witness and symbol of one's conversion.
Another perspective on this verse from a Free Grace position is that the "baptism" of Mark 16:16 refers to the baptism of the Spirit, which all believers are partakers of, when we are sealed with the Spirit after faith (Ephesians 1:12-14), and "baptized" into the body of Christ (1 Corinthians 12:13). This is the "one baptism" (Ephesians 4:5) shared by all children of God.
In this view, Mark 16:16 is specifically in reference to the outpouring of the Spirit on the day of Pentecost, which was called being "baptized with the Holy Ghost" in the parallel account of the same event in Acts chapter 1:
Acts 1:5-9
5 For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence.
6 When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?
7 And he said unto them, It is not for you to know the times or the seasons, which the Father hath put in his own power.
8 But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth.
9 And when he had spoken these things, while they beheld, he was taken up; and a cloud received him out of their sight.
Mark 16:16-19
16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
17 And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;
18 They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.
19 So then after the Lord had spoken unto them, he was received up into heaven, and sat on the right hand of God.
Notice above that Mark 16:19 matches Acts 1:9 - these passages cover the same event. And, in the passage in Acts, the Lord contrasts a water baptism with the baptism of the Holy Ghost "not many days hence", the account of the fulfillment of which is given in Acts 2:2-4, and it had accompanying it "signs and wonders" (Acts 2:22, 2:43).
Therefore, it's a Biblically defensible position that the "baptism" in Mark 16:16 is not even referring to water baptism at all.
The subject of Baptismal Regeneration received its own spotlight in this article, so please refer to that for further reading.
It is a false doctrine that teaches works Salvation, as in many parts of the world, even until today, a public baptism can lead to ostracization, persecution, and even death. It is also a doctrine that totally misunderstands the doctrine of the new birth.