"If anyone secretly entices you—even if it is your brother, your father's son or your mother's son, or your own son or daughter, or the wife you embrace, or your most intimate friend—saying, 'Let us go and worship other gods', whom neither you nor your ancestors have known, any of the gods of the peoples that are around you, whether near you or far away from you, from one end of the earth to the other, you must not yield to or heed any such persons. Show them no pity or compassion and do not shield them. But you shall surely kill them; your own hand shall be first against them to execute them, and afterwards the hand of all the people. Stone them to death for trying to turn you away from the LORD your God, who brought you out of the land of Egypt, out of the house of slavery. Then all Israel shall hear and be afraid, and never again do any such wickedness." (NRSV 13:6-11)
If thy brother, the son of thy mother, or thy son, or thy daughter, or the wife of thy bosom, or thy friend, which is as thine own soul, entice thee secretly, saying, Let us go and serve other gods, which thou hast not known, thou, nor thy fathers; Namely, of the gods of the people which are round about you, nigh unto thee, or far off from thee, from the one end of the earth even unto the other end of the earth; Thou shalt not consent unto him, nor hearken unto him; neither shall thine eye pity him, neither shalt thou spare, neither shalt thou conceal him: But thou shalt surely kill him; thine hand shall be first upon him to put him to death, and afterwards the hand of all the people. And thou shalt stone him with stones, that he die; because he hath sought to thrust thee away from the Lord thy God, which brought thee out of the land of Egypt, from the house of bondage. And all Israel shall hear, and fear, and shall do no more any such wickedness as this is among you. (KJV 13:6-11)
Didn't we just see "Thou shalt not kill"? What gives? Well, we know that worshipping idols is pretty much the lowest low in Deuteronomy, so if there's going to be an exception, it would be here. Stone away, Israelites.