Principal purpose of Torah is destruction of idolatry

 Moreh Nevuchim (3:29) You know from the repeated declarations in the Law that the principal purpose of the whole Law was the removal and utter destruction of idolatry, and all that is connected therewith, even its name, and everything that might lead to any such practices The law prohibits us to imitate the heathen in any of these deeds, and a fortiori to adopt them entirely. It is distinctly said in the Law that everything which idolaters consider as service to their gods, and a means of approaching them, is rejected and despised by God; comp. "for every abomination to the Lord, which he hateth, have they done unto their gods" (Deut. 12:3 1). In the books which I shall name to you later on, it is stated that on certain occasions they offered to the sun, their greatest god, seven beetles, and seven mice, and seven bats. This alone suffices to show how disgusting their practice must be to human nature. Thus all precepts cautioning against idolatry, or against that which is connected therewith, leads to it, or is related to it, are evidently useful. They all tend to save us from the evil doctrines that deprive us of everything useful for the acquisition of the twofold perfection of man, by leading to those absurd practices in which our fathers and ancestors have been brought up. It is in reference to these idolatrous ideas that the true prophets exclaim, "They walked after vain things, which do not profit." How great is the usefulness of every precept that delivers us from this great error, and leads us back to the true faith: that God, the Creator of all things, rules the Universe: that He must be served, loved, and feared, and not those imaginary deities. According to this faith we approach the true God, and obtain His favour without having recourse to burdensome means: for nothing else is required but to love and fear Him; this is the aim in serving God, as will be shown. Comp. "And now, Israel, what doth the Lord thy God require of thee but to fear the Lord"? etc. (Deut. 10:12). I shall complete this subject later on: now let us return to the theme [of this chapter]. I say that my knowledge of the belief, practice, and worship of the Sabeans has given me an insight into many of the divine precepts, and has led me to know their reason. You will confirm it when I shall give the reason of commandments which are seemingly purposeless. I will mention to you the works from which you may learn all that I know of the religion and the opinions of the Sabeans; you will thereby obtain a true knowledge of my theory as regards the purpose of the divine precepts. The great book on this subject is the book On the Nabatean Agriculture,

Moreh Nevuchim (3:37) It is the object and centre of the whole Law to abolish idolatry and utterly uproot it, and to overthrow the opinion that any of the stars could interfere for good or evil in human matters, because it leads to the worship of stars.