Conversion to Christianity requires a belief in substitutionary atonement, that Jesus Christ died for the convert's sins. Baptism is a rite observed in virtually every sect of Christianity. Sects differ on the nature and meaning on baptism with Catholic, Orthodox, Anglican, Lutheran, and Churches of Christ among other sects believing that baptism forgives sins, while Baptists and other sects believe baptism to be an ordinance and an act of obedience as an outward sign of an inward acceptance of Christ.
Catholics, Orthodox, Anglicans, and Lutherans all require education before formal conversions into their sects may occur. Roman Catholics refer to this education as catechism and adult converts will participate in a program called Rite of Chrisitan Initiation for Adults (RCIA) and many parishes offer a similar program for children above the age of accountability called RCIC. Anglicans offer similar classes for adults and child converts in addition to typcial confirmation classes.
Conversion to Judaism requires a period of study under a Rabbi. An ancient Jewish tradition is for the Rabbi to turn away prospective converts three times, to test the convert's dedication to Judaism and sincerity in desiring to convert. Many Rabbis, especially in non-Orthodox Jewish sects, do not do this in the modern age.
For those who are not ethncially Jewish, or if Jewish ethnicity is in question, conversion is necessary to become a Jew. Once the period of study under the rabbi is completed, one is taken to a religious court where at least three Jews, and at least one of whom is a rabbi, and they decide whether the individual has fulfilled the requirements of study, sincerity, and living a Jewish lifestyle while immersing onself in the Jewish community. If this goes successfully, the individual is considered a Jew. Males and females are given a ritual bath, and males are circumcised. In the event that a male is already circumcised, a symbolic circumcision occurs when a drop of blood is drawn from the circumcised area. Although in Reform Judaism, those rituals are optional, and Reform conversions are considered invalid in all other sects of Judaism. Orthodox Judaism considers most non-Orthodox conversions invalid.
Conversion to Islam requires a sincere testimony of faith where one states that there is no God but Allah, and that Muhammad is the messenger of Allah. This is referred to as the Shahada and is said in Arabic "La ilaha Illa Allah Muhammad Rasulu llah."