Apostasy in judaism

In Judaism, apostasy refers to the rejection of Judaism and possible defection to another religion by a Jew. The term apostasy is derived from Ancient Greek: ἀποστάτης, meaning "rebellious" (Hebrew: מרד‎‎.) Equivalent expressions for apostate in Hebrew that are used by rabbinical scholars include mumar (מומר, literally "the one that was changed"), poshea Yisrael (פושע ישראל, literally, "transgressor of Israel"), and kofer (כופר, literally "denier"). Similar terms are meshumad (משומד, lit. "destroyed one"), one who has abandoned his faith, and min (מין) or epikoros (אפיקורוס), which denote the negation of God and Judaism, implying atheism.

The first recorded reference to apostasy from Judaism is in Deuteronomy 13:6-11, which states:

"If your very own brother, or your son or daughter, or the wife you love, or your closest friend secretly entices you, saying, "Let us go and worship other gods" (gods that neither you nor your fathers have known, gods of the peoples around you, whether near or far, from one end of the land to the other), do not yield to him or listen to him. Show him no pity. Do not spare him or shield him. You must certainly put him to death. Your hand must be the first in putting him to death, and then the hands of all the people. Stone him to death, because he tried to turn you away from the LORD your God, who brought you out of Egypt, out of the land of slavery. Then all Israel will hear and be afraid, and no one among you will do such an evil thing again."

In the Talmud, Elisha ben Abuyah (referred to as Acher, the "Other One") is singled out as an apostate by the rabbis.

In Medieval Spain, a systematic conversion of Jews to Christianity took place, largely under threats and force. The apostasy of these conversos provoked the indignation of some Jews in Spain and it was made illegal to call a converso by the epithet tornadizo (renegade).

...
Wikipedia