I think you might be asking the wrong question.
These verses indicate Baptism is a common experience to all believers. It doesn't appear optional.
Romans 6 3Or don't you know that all of us who were baptized into Christ Jesus were baptized into his death? 4We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.
5If we have been united with him like this in his death, we will certainly also be united with him in his resurrection.
Ephesians 4 4There is one body and one Spirit—just as you were called to one hope when you were called— 5one Lord, one faith, one baptism; 6one God and Father of all, who is over all and through all and in all.
Colossians 2: 11In him you were also circumcised, in the putting off of the sinful nature,[
a] not with a circumcision done by the hands of men but with the circumcision done by Christ, 12having been buried with him in baptism and raised with him through your faith in the power of God, who raised him from the dead.
Baptism seems closely linked to being saved..
Mark 16: 15He said to them, "Go into all the world and preach the good news to all creation. 16Whoever believes and is baptized will be saved, but whoever does not believe will be condemned. 17And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues;
Acts 2: 37When the people heard this, they were cut to the heart and said to Peter and the other apostles, "Brothers, what shall we do?" 38Peter replied, "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit. 39The promise is for you and your children and for all who are far off—for all whom the Lord our God will call."
Others verses say salvation is merely by grace and through faith, not of any work.
Ephesians 2:
8For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— 9not by works, so that no one can boast. 10For we are God's workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do.
James calls on believers to have works as evidence of their faith.
James 2: 20You foolish man, do you want evidence that faith without deeds is useless[
d]? 21Was not our ancestor Abraham considered righteous for what he did when he offered his son Isaac on the altar? 22You see that his faith and his actions were working together, and his faith was made complete by what he did. 23And the scripture was fulfilled that says, "Abraham believed God, and it was credited to him as righteousness,"[
e] and he was called God's friend. 24You see that a person is justified by what he does and not by faith alone. 25In the same way, was not even Rahab the prostitute considered righteous for what she did when she gave lodging to the spies and sent them off in a different direction? 26As the body without the spirit is dead, so faith without deeds is dead.
The man who died on the cross next to Jesus was heaven bound and he wasn't baptized.
Luke 23:
42Then he said, "Jesus, remember me when you come into your kingdom.[
a]" 43Jesus answered him, "I tell you the truth, today you will be with me in paradise."
So i would say baptism is a sign of obedience that shows faith is at work in you. It's a vital part of our Christian experience. So the question isn't, "Is baptism required?" The real question is, "Why would an obedient heart changed by grace not seek to be baptized?"
And in extreme circumstances where someone can't be baptized, I'd say God takes that in to consideration and lets the person get to heaven.