"If your brother, the son of your father or of your mother, or your son or daughter, or the spouse whom you embrace, or your most intimate friend, tries to secretly seduce you, saying, “Let us go and serve other gods,” unknown to you or your ancestors before you, gods of the people surrounding you, whether near you or far away, anywhere throughout the world, you must not consent, you must not listen to him; you must show him no pity, you must not spare him or conceal his guilt. No, you must kill him, your hand must strike the first blow in putting him to death and the hands of the rest of the people following. You must stone him to death, since he has tried to divert you from Yahweh your God…"
One of the most horrific passages in the Bible. If this was written in any other type of book (philosophical, political, etc.) we would all say it was immoral. But with religion, one can get away with worshiping a text that commands you to kill.