Immersion in water does nothing but serve as a public expression of commitment. Peter spoke of the contrast between that which merely washes dirt from the body and that which cleanses the spirit. Paul also made several indications that this rite was not part of the gospel and something he was happy he hadn't done to many people. Even John the Baptist said that what he was doing was to be but a shadow of what was to come: the baptism of fire, meaning the Holy Spirit indwelling a person at the moment of belief. Even in Acts, the Spirit came sometimes before baptism and sometimes after, clearly indicating its irrelevance to salvation.

I've also stated many times in these threads that salvation, being a reconciliation with God, means no longer living in a way that grieves or ignores God. As Paul said, "We died to sin; how can we keep living in it?"

But the Ten Commandments were strictly for the nation of Israel. As the writer of Hebrews states clearly in chapter 7, with a change of priesthood comes a change of law. As Jesus said in the parable of the wineskins, you cannot mix old and new. As Paul said, the law was a custodian, a shadow, but the reality is Christ. And as John said, our new law is simply to love God and others, which Paul summed up as "Love does no harm to its neighbor, therefore love is the fulfillment of the law". Even James, who some think taught salvation by works (I disagree), said that the law was "a burden neither we nor our ancestors could bear", such that Gentiles would not need to practice Judaism to be saved.

Jesus set us free from legalism and from sin. He set us free from "dead works", rituals, temples, and regulations. "Where two or three gather in [His] name" and "neither here nor there but in spirit and truth", living in close relationship with Jesus, is how to practice Christianity. Our righteousness does not come from ourselves but only in Jesus.