Baptist
Pre-Christian ReligionsThe practice of baptism in pagan religions seems to have been based on a belief in the purifying properties of water. In ancient Babylon, according to the Tablets of Maklu, water was important as a spiritual cleansing agent in the cult of Enke, lord of Eridu. In Egypt, the Book of Going Forth by Day contains a treatise on the baptism of newborn children, which is performed to purify them of blemishes acquired in the womb. Water, especially the Nile's cold water, which was believed to have regenerative powers, is used to baptize the dead in a ritual based on the Osiris myth. Egyptian cults also developed the idea of regeneration through water. The bath preceding initiation into the cult of Isis seems to have been more than a simple ritual purification; it was probably intended to represent symbolically the initiate's death to the life of this world by recalling Osiris' drowning in the Nile.
In the cult of Cybele, a baptism of blood was practiced in the rite of the Taurobolium: where one was covered with the blood of a bull. At first this rite seems to have been to provide the initiate with greater physical vitality, but later it acquired more of a spiritual importance. A well-known inscription attests that he who has received baptism of blood has received a new birth in eternity. However, the fact that this baptism was repeated periodically shows that the idea of complete spiritual regeneration was not associated with it.
The property of immortality was also associated with baptism in the ancient Greek world. A bath in the sanctuary of Trophonion procured for the initiate a blessed immortality even while in this world. The mystery religions of that period often included ablution rites of either immersion or a washing of the body for the purposes of purification or initiation. Other concepts said to have been associated with these forms of cultic baptisms included the transformation of one's life, the removal of sins, symbolic representation, the attainment of greater physical vitality, a new beginning, spiritual regeneration. It is believed that all ancient religions recognized some form of spiritual cleansing, renewal or initiation that was accomplished through a washing or immersion in water.
JudaismThe liturgical use of water was common in the Jewish world. The Law of Moses required ablutions (washings) on the part of priests following certain sacrifices and on certain individuals who were unclean because of an infectious disease (Num. 19:1-22; Lev 14,15, 16:24-28). The natural method of cleansing the body by washing and bathing in water was always customary in Israel. The washing of their clothes was an important means of sanctification imposed on the Israelites even before the law was given a Mt. Sinai (Ex 19:10). The use of water for cleansing was used symbolically as well in such passages as Eze 36:25 where God says, "I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your impurities . . ." We do not believe that the practice of baptism for the remission of sins as taught in the New Testament was based in any way on the Old Testament, however the Old Testament washings with or in water that were for the purpose of physical cleansing can be seen as a type or shadow of New Testament baptism, which is for the purpose of spiritual cleansing (1 Peter 3:21).
Toward the beginning of the Christian era, the Jews adopted (as a custom unrelated to Divine guidance) the custom of baptizing proselytes seven days after their circumcision. A series of specific interrogations made it possible to judge the real intentions of the candidate who wished to adopt the Jewish religion. After submitting to these interrogations, he was circumcised and later baptized before witnesses. In the baptism, he was immersed naked in a pool of flowing water; when he rose from the pool, he was a true son of Israel. After their baptism, new converts were allowed access to the sacrifices in the Temple.
http://www.bible.ca/ef/topical-baptism-a-prechristian-history.htm