Idolatry was the chief sin mentioned in the Old Testament that the Israelites struggled with, and that means that most likely, it is the same with us today. But, can an ancient and harsh text really contain contemporary wisdom for our situation?
If a prophet, or one who foretells by dreams, appears among you and announces to you a miraculous sign or wonder, and if the sign or wonder of which he has spoken takes place, and he says, “Let us follow other gods” (gods you have not known) “and let us worship them,” you must not listen to the words of that prophet or dreamer. The Lord your God is testing you to find out whether you love him with all your heart and with all your soul. It is the Lord your God you must follow, and him you must revere.
Keep his commands and obey him; serve him and hold fast to him. That prophet or dreamer must be put to death, because he preached rebellion against the Lord your God, who brought you out of Egypt and redeemed you from the land of slavery; he has tried to turn you from the way the Lord your God commanded you to follow. You must purge the evil from among you.
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.
New International Version, 1984 Edition