If you insist that baptism isn't essential for salvation, what is your take on these scriptures?
John 3:5 Jesus answered, “Truly, truly, I say to you, unless someone is born of water and the Spirit, he cannot enter the kingdom of God.
Acts 2:38 Peter said to them, “Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit.
Acts 22:16 Now why do you delay? Get up and be baptized, and wash away your sins by calling on His name.’
Romans 6:2-7 Far from it! How shall we who died to sin still live in it? Or do you not know that all of us who have been baptized into Christ Jesus have been baptized into His death? Therefore we have been buried with Him through baptism into death, so that, just as Christ was raised from the dead through the glory of the Father, so we too may walk in newness of life.
For if we have become united with Him in the likeness of His death, certainly we shall also be in the likeness of His resurrection, knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin; for the one who has died is freed from sin.
Galatians 3:27 For all of you who were baptized into Christ have clothed yourselves with Christ.
Colossians 2:11 having been 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.
Titus 3:4-5 He saved us, not on the basis of deeds which we did in righteousness, but in accordance with His mercy, by the washing of regeneration and renewing by the Holy Spirit
1 Peter 3:21 Corresponding to that, baptism now saves you—not the removal of dirt from the flesh, but an appeal to God for a good conscience—through the resurrection of Jesus Christ
If you take all of these verses at face value, it should become obvious to you that in baptism we are united to Christs death and resurrection and our sins are remitted. As far as I know, that is what the early Christians did, so that was the universal belief among them.
Regarding the thief on the cross: Do you believe it is essential to believe in the resurrection of Jesus for salvation? If yes (I expect that is your answer), how did the thief on the cross get to paradise? He couldn't believe in the resurrection as it had not happened yet!
How did righteous Abel, Noah, Enoch, Abraham, etc. got saved as they could not believe in the gospel? It would be absolutely ridiculous to say, oh, so obviously you don't need to believe in Jesus after all if they made it without doing so. So ask yourself the question: is it reasonable to use the example of the thief on the cross, who didn't even have the chance to be baptized after his repentance, which happened right there on the cross?
It is very obvious to me that God can save people without baptism if it is his pleasure to do so. But he has made it very clear that we are to be baptized and by this baptism in Jesus' name we are actually united to his death and his resurrection. There is not a single verse in scripture that says it is about a public confession or commitment (in fact there are instances in the book of Acts where it is very obvious that it wasn't public at all - e.g.
the Ethiopian Eunuch in chapter 8 and the Philippian jailor and his family in chapter 16) nor is there any scripture that says it is only a symbolic act.
If you haven't done so already, I recommend you to listen to David Bercot's message on what the Early Christians believed about baptism.