Avodas Kochavim 2:5
A Jew who worships idols is considered like a non-Jew in all regards; he is not the same as a Jew who violated any other sin that carries the penalty of death by stoning. An apostate who worships idols is considered an apostate to every matter in the Torah. Similarly, Jewish heretics are not considered Jews in any way and their repentance should not be accepted, as per Proverbs 2:19, “None who go to her return, nor do they attain the paths of life.” This refers to heretics who stray after the thoughts of their hearts, occupying themselves with the foolish things discussed above, until they violate the principles of Torah with the intention of spiting God, saying that doing so is not a sin. We are not allowed to talk to such people or even to respond to them, as per Proverbs 5:8, “Do not come near the door of her house.” A heretic’s thoughts are likely filled with heresy.
Avodas Kochavim 2:6
Whoever accepts an idol as true, even if he does not actually worship it, blasphemes against God’s great name. This applies both to a person who worships idols and to one who curses God, as per Numbers 15:30, “The one who does so with a high hand, whether born Jewish or a convert, blasphemes against God.” Therefore, a person who worships idols is hanged after execution, just like one who blasphemes. Both are executed by stoning. For this reason, the laws of a blasphemer are included in the section on idolatry, as both kinds of offender deny basic foundations of Judaism.