The Talmud says that COMPLETE renunciation of idolatry leads inexorably to One-Law:
"Hence we learn that those who follow idolatry deny as it were their adhesion to the whole Law, and those who reject idolatry follow as it were the whole Law,' (B.T. Kidd, 40a).
By the way, lest anyone fall for the lies of Derek Leman and the UMJC, note that the One-Law principle (the principle that those People bound to the Sinaitic Torah were bound to a general law or, as I like to put it in lawyerly terms: within Israel, all common citizens of the same gender are bound to the same mitzvot) is taught by the Sages. As I've already shown this to be the case with Rashi, here is Rambam on the subject:
"For this reason it would not be right to make the fundamental principles of the Law dependent on a certain time or a certain place; on the contrary, the statutes and the judgments must be definite, unconditional, and GENERAL in accordance with the divine words: 'As for the congregation, one ordinance shall be for you and for the stranger' (Num. xv. 15); they are intended, as has been stated before, FOR ALL PERSONS AND FOR ALL TIME," (The Guide, part III, chapter XXXIV).
We've also previously discussed how Maimonides (Rambam) explains the two-stage process of conversion in Part III of the Guide in which he discusses the rationales for the mitzvot (I'll do a post on that in just a few more minutes). For example, he says:
"The knowledge of these [pagan] theories and practices is of great importance in explaining the reasons of the precepts. For it is the principal object of the Law and the axis around which it turns, to blot out these opinions from man's heart and make the existence of idolatry impossible,"
[After quoting Deut. 6:24] "He thus says that even every one of these 'statutes' convinces all nations of the wisdom and understanding it includes."
"...[G-d] gave the [mitzvot] as a means of securing His chief object, viz., to spread a knowledge of Him [among the people], and to cause them to reject idolatry."
To sum up Rambam, the Torah is given to (1) totally eliminate idolatry and (2) show everyone (Deut. 6:24) that the Torah contains wisdom "for all persons and for all time".