Although baptism probably has its roots in the Mikva, which is a ritual cleansing, that's not really the significance within Christianity. Baptism is not a washing away of sins, or impurity, but is rather a symbolic death and resurrection. The Apostle Paul, an early codifier of Christian doctrine whose letters became part of the Christian Bible wrote as follows in Romans chapter 6

Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? Therefore we have been buried with him by baptism into death, so that, just as Christ was raised from the dead by the glory of the Father, so we too might walk in newness of life.

This has the same end effect- the removal of sin and purification, but the conception is totally different.

[–] theneverfox@pawb.social 2 points 16 hours ago

Jesus was a revolutionary. He removed all weaknesses that could be used against the Jewish people, from temples to stockpiles to using money. He made the early church suck resources from an occupying force while giving nothing back, not even disobedience that could justify a crack down

In this process, he replaced many rituals with simpler versions that can be done without any special requirements. He reworked every ritual so that it couldn't be taken away, it couldn't be used to force compliance

Paul was a true believer and philosopher, his job was to sell it to the people. His words were canonized alongside the gospels because they were convenient when reframing Jesus's teachings with the values of the Roman religion... Plenty less convenient writings were buried instead

Paul was a transitional figure who found himself in between the early church and unexpected gentile converts... He had to rebrand the rituals for a wider audience while keeping the core message. Nothing against the guy... He was in an impossible position and did his best