One Who Believes In Hashem but Accepts a Religion or Ideology that Rejects Compliance with the Commandments Is Like One Who Accepts Idolatry
In the Biblical book of Deuteronomy chapter 11 verse 28: Hashem decrees a curse, “if you will not listen to the commandments of Hashem your L-rd, but turn aside out of the way which I command you this day, to go after other deities that you have not known”.
Sifri comments on the verse:” but turn aside out of the way which I command you this day, to go after other deities: From here we derive that anyone that admits to Foreign Worship (Idolatry) completely denies the entire Torah and anyone that denies Foreign Worship (Idolatry) admits completely to the entire Torah”.
It is reasonable to assume both sides of the equation are true, namely, Idolatry = Denial of Torah and Denial of the Torah that was revealed to Moshe (at least for Kiddush Hashem purposes) = Idolatry. But since there is room to quibble that the equation doesn’t work in both directions, it is fitting to bring additional proof.
Rabbi Shimshon B. R. Raphael Hirsch explained the Biblical verse quoted above in the following way:
But turn aside, etc. to go after, etc.: every step that distances us further from the commandments draws us nearer to Foreign Worship {Idolatry}. “From here they derived, that anyone, that admits to Foreign Worship {Idolatry} completely denies the entire Torah and anyone that denies Foreign Worship {Idolatry} admits completely to the entire Torah” (Sifri). It appears to us that it is not redundant to comment: In these statements, it was stated the exact opposite of that fabricated principle, that it is sufficient for a Jew, to “believe in Hashem” – even if he turns his back {lit. the back of his neck} to all the commandments of Hashem. Behold it is stated here that the admission to all the Torah in its entirety – that is to say: the admission of the obligation to fulfill all the commandments of Hashem – is connected in an unbreakable link to the admission or rejection of the unity of Hashem. “The belief in Hashem” of Judaism is not just a belief in the existence of Hashem, alone, rather it is an admission of the sovereignty of Hashem upon us that brings us to subjugate ourselves to his will. The Jewish belief in the unity of Hashem is “the acceptance of the yoke of heaven”: a subjugation of our destiny and our deeds to the one, Almighty G-d; therefore one who denies Foreign Worship is like one who admits to the whole Torah in its entirety. The denial of the unity of Hashem, the admission to another deity outside of the one Almighty G-d – or at his side – is Foreign Worship (Idolatry) in its simple obvious meaning, for it is “subjugation to another”, uprooting of our being and our obligation from the sole dictates of the one Almighty G-d. Therefore one that admits to Foreign Worship is like one who rejects all the Torah in its entirety. And indeed, the source that these statements are derived from, does not leave any doubt about this matter, for behold the source of these statements are:
but turn aside out of the way, etc. to go after other deities. However, this verse does not say that one that admits to Foreign Worship (Idolatry) is like one who rejects the entire Torah, rather the wording is the opposite; for it was stated here that any deviation from the way of the commandments, similar to this is the going in the way of Foreign Worship (Idolatry), that is to say : anyone that denies the Torah is like admitting to Foreign Worship (see also the commentary to the Biblical book of Numbers, chapter 15 verse 31 and there is {presented} an explanation that a Mumar Lehachis {an ideological sinner} even in just one area is like one who serves Foreign Worship {Idolatry}.