issues about Christianity that come up in the Rambam is that of idolatry.

One of the issues about Christianity that come up in the Rambam is that of idolatry. The problem is that most any type of religious worship involves going to God through some kind of middle step. It is rare that people think that just by learning Torah and keeping it that they will be doing OK. The entire religious world in fact usually is worshiping some kind of human. The question rather seems to be who really is connected with God. Who is from the realm of holiness. In any case this come up in tractate Avoda Zara in Tosphot. [I forget the page-but it is where the issue of "joining" comes up. I think that Christians leaned heavily towards Plato and eventually Plotinus because of the problems with the trinity. The Neo-Platonic approach seemed to help for about a thousand years. the problem obvious was how to preserve Divine Simplicity. Eventually Aquinas decided that the Neo-Plato approach just was not helping so he went along with Aristotle as had did Rambam for the same reasons. after all Ibn Gavirol and the Chovot Levavot obligations of the hearts had been neo platonic. Clearly, Muslims had already been going more or less with Aristotle for the same reason. With Aristotle, it is easy to preserve Divine Simplicity.