Mark 16:16 says, "He who believes and is baptized will be saved; but he who does not believe will be condemned." It does not say, "...but he who does not believe and is not baptized will be condemned." this is reading something into the passage that is not there. So why should baptism be essential for salvation?
Thanks for the question,
Mk. 16:16 is not a statement from a legal document. Jesus wasn't a lawyer, nor did he want his disciples to be lawyers or ecclesiastical adjudicators. This is Mark's account of the commission that Jesus gave to his disciples just before he ascended into heaven. It's a clear command using simple language.
Parallel passages are:
Mt. 28:18-20 "And Jesus came and spoke unto them, saying, All power is given unto me in heaven and in earth. Go you therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the age. Amen. "
Mk. 16:15-16 "And he said unto them, Go you into all the world, and preach the gospel to every creature. He that believes and is baptized shall be saved; but he that believes not shall be damned."
Lk. 24: 46-47 "And said unto them, Thus it is written, and thus it behooved Christ to suffer, and to rise from the dead the third day: And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem."
Combining these three accounts you can see that Jesus was given all authority and that he sent his disciples into the whole world, to preach the good news to every creature. The person who believes, repents, is baptized and gains remission of sins will be saved. The person who does not believe will be damned.
Ten days later on the day of Pentecost, Peter preached the gospel to many Jews in Jerusalem. When their hearts were convicted that they had murdered their own Messiah, meaning that they believed what Peter was preaching, he told them to repent and be baptized for the remission of sins, and they would receive the gift of the Holy Spirit.
Acts 2:36-38 "Therefore let all the house of Israel know assuredly, that God hath made the same Jesus, whom you have crucified, both Lord and Christ. Now when they heard this, they were cut to the heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do? Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and you shall receive the gift of the Holy Spirit."
So Peter preached exactly what Jesus told him to preach. Something that you very seldom hear from any preacher today. Why?
Because they are holding to a doctrinal position of the Baptist church formulated on what John Calvin and Martin Luther taught, even when the Bible they hold in their hand says something different. But who will they follow?
The person who does not believe the words of Jesus will not be baptized for the remission of sins. The person who does not teach or preach the words of Jesus will not be baptized for the remission of sins. The person who joins a church that teaches something different than the words of Jesus will not be baptized for the remission of sins. Jesus didn't have to say it - it goes without saying.
"He that believes and is baptized will be saved. He that does not believe will be damned."
He that comes to the United States and takes the oath of citizenship will become an American. But he that does not come to the United States will remain a foreigner.
He that comes to my dinner party and opens a gift will have a pleasant surprise. But he that does not come to my party will be unhappy.
He that opens a can of soda and drinks of it will be refreshed. But he that does not open the can of soda will remain thirsty.
Will a person who does NOT believe in Jesus be baptized for the remission of sins? Obviously not. It takes faith to be baptized. Faith in God.
Why should baptism be essential for salvation?
First of all because the Lord commanded it, which is reason enough. But secondly, to understand we need to consider that when we are saved we enter into a covenant with God - the New Covenant. (Jer. 31:31)
The Messiah was given as a covenant to the people. (Isa. 49: 8) Therefore we need to be in Christ to be in a covenant relationship with God. We are baptized into Christ which makes us part of that covenant.
"For you are all sons of God through faith in Christ Jesus. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus. And if you are Christís, then you are Abrahamís seed, and heirs according to the promise."
Just as circumcision was the sign of the covenant between Israel and Jehovah, we are spiritually circumcised in putting off the body of the sins of the flesh when we are baptized.
"In him you were also circumcised with the circumcision made without hands, by putting off the body of the sins of the flesh, by the circumcision of Christ,
buried with him in baptism, in which you were also raised with him through faith in the working of God, who raised him from the dead. And you, being dead in your trespasses and the uncircumcision of your flesh, he has made alive together with him, having forgiven you all trespasses"
We die with Jesus and become one with him in his death and united with him also in his resurrection. (Rom. 6) As the above passage states, we are raised from death by our faith in the working of God. The working of God that we have faith in is that he is forgiving us all our trespasses and is making us spiritually alive in Christ Jesus when we are baptized.
We are spiritually alive because when we are baptized God gives to us the gift of the Holy Spirit who communicates that life to us in the name of Jesus. (Acts 2:38-39; 2Cor. 3:6)
This quickening by the Holy Spirit is what it means to be born of the Spirit. When we are baptized we are born of the water and the spirit and we enter the kingdom of God. (Jno. 3: 5) We are regenerated.
Baptism is not a work of righteousness for it's own sake. Standing alone it has no significance. But by faith in the death, burial and resurrection of Jesus it becomes the moment that God saves us.
"... not by works of righteousness which we have done, but according to his mercy he saved us, through the washing of regeneration and renewing of the Holy Spirit, whom he poured out on us abundantly through Jesus Christ our Savior,"
The washing of regeneration is obviously different words for the bath of the new birth - being born of water. The renewing of the Holy Spirit is being born of the Spirit. (Jno.3)
Therefore, Jno. 3:5; Acts 2:38; Rom. 6; Col. 2:12-13; and Tit. 3:5-6 all agree together and tell us that Baptism is essential. It is where and when we have saving faith in Jesus Christ and God the father who raised him from the dead.
Hope this helps.