Baptism is a representation of us being born into Christ. It is something every Christian should do. It is not something one should do to be saved. Putting baptism as a requirement for salvation makes Jesus’ sacrifice not enough for our salvation and with this I disagree.
It was Jesus Christ who commanded, "Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age" (Matthew 28:19-20). So in essence you are saying that Jesus' command to make disciples of all nations via baptism nullified his own sacrifice. Such is obviously false.
You claim that baptism is not connected with salvation, but I find in the Bible:
"He who believes and is baptized will be saved; but he who does not believe will be condemned" (Mark 16:16).
"Then Peter said to them, "Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit"" (Acts 2:38).
"And now why are you waiting? Arise and be baptized, and wash away your sins, calling on the name of the Lord" (Acts 22:16).
"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" (I Peter 3:21).
Baptism is a represention. The power of baptism is not in the water, but in the things that it represents. (Just as the Lord's Supper is not just unleaven bread and fruit of the vine, but that these two elements represent Jesus' body and shed blood (I Corinthians 11:23-26).)
Baptism represents Jesus death, burial, and resurrection. "Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death? Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been united together in the likeness of His death, certainly we also shall be in the likeness of His resurrection, knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin. For he who has died has been freed from sin" (Romans 6:3-7). Entering the water represents Jesus' death. Being under water represents Jesus' burial. Coming up out of the water represents Jesus' ressurection. Hence, baptism doesn't replace Jesus' sacrifice, it is a representation of that sacrifice that brought us salvation.
Simultaneously, baptism also represents a person's death to sin, his resurrection to a new life, and his hope of his future resurrection at Christ's return by this same passage in Romans. It is through the water of baptism that we contact the saving power of Jesus' death. In the watery grave we die to sin and rise up to a new life freed from sin. This is way baptism is also referred to as a birth, which you correctly noted at the beginning of your point. The power for the new birth and the freedom from sin is found in Jesus' death. Baptism represents that conversion. Baptism doesn't make Jesus' death inadequate for salvation, it declares that Jesus' death saves!
"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 also were raised with Him through faith in the working of God, who raised Him from the dead" (Colossians 2:11-12). Baptism is a working of God. Being baptized is a declaration of faith in God's work. If a person is not baptized, then they are saying they do not believe in the power of God to save them from sin.