A core belief of many forms of Christianity is the performing of Baptism. Some find Baptism as a right of passage into the family of God others have the belief that without Baptism entrance into Heaven is not possible. The word ‘baptism’ is a Greek word that literally means ‘to immerse or to dip’. Whichever your belief if any on the matter, here is a basic retelling of how the ritual of Baptism came to be.
Originally Baptism was a purification ritual adapted from the Jewish faith and performed by the priests at the temple to make someone who was deemed as unclean back into being clean and presentable in the eyes of God. This could be from touching an unclean person, the dealing with the dead or diseased, being with a woman during menstruation, or any number of other things that the Torah had determined as ‘unclean’. The ritual had the person being cleansed bringing the appropriate offering, such as doves, lambs, or sometimes simply just grains, to the priest and having the priest say the appropriate words to God before ‘washing’ the unclean person in the waters, oils, and/or perfumes at the temple. This procedure was symbolic of the uncleanliness going from the person to the water, therefore allowing the person being baptized to enter the Temple for worship on Saturday as the holy day.
At the start of Christianity, being as it was at that time a small cult branching from the mother religion of Judaism, they kept the practice of washing away the sins through the symbolic act, as Jesus was washed and performed the washing from John the Baptist. They did not ask for an offering to the priest, just a vow and oath of belief in the Christian religion and all that they stood for.
Most Baptisms from the early 30s AD until the Roman Empire took control of the religion in the early 300s AD were done in rivers. Anywhere from a few (25 to 50) up to thousands reportedly, usually entire families from the new born and children through the parents, Aunts and Uncles, to grandparents and the extremely aged. They were performed mostly the same with the convert being completely nude as two priests helped them enter the body of water on one side, two in the middle submerging them as the word of baptism were offered to God on the recipients behalf, and two more aiding the new member into a white robe (symbolic of the white light of the Holy Spirit that was now within them) as they exited on the other side of the river completing the ceremony it was also symbolic of the new rebirth of the individual as the waters of the river representing the waters of child birthing.
After the Roman Empire had its influences into the early Catholic doctrine the new converts were required to be clothed as the only real change that the ritual was to undergo at that time. Baptism went for many years without change until the Catholic Church made the distinction that full immersion was no longer necessary in 1311 at the Council of Ravenna. They determined that full immersion was unnecessary and the term ‘pouring’ was the new accepted way of performing the baptism. Many denominations chose to go back to the immersion technique after the reformation in the 16th and 17th centuries.