You state that it would need to be taught carefully but I'm unsure of if it could ever be implemented.
Do we teach that Jesus was crucified as Christians believe (not even getting into resurection or whether He was the Son of God in the classroom) or teach the Muslim belief that he was not killed?
Do we point-by-point counter "Christians believe this about Jesus but Muslims believe that, while some Jews believe...."?
Do we break it down further to "Catholics believe... while Baptists believe... while Presbyterians believe... while Methodists believe..."?
Do we learn about each of the cultural origins of each discipline of Christianity? Do we tie all of this to changes in the role in Judeo-Christian faith in the land of America?
Yes, you would teach that in orthodox Christianity, Jesus is fully divine and fully human; and that in jewish belief this violates monotheism - and then how the trinitarian theology addresses this. Then in Islam, the strong teaching that God was not begotten and did not beget…
You would also compare what the religions share: the transcendant, the absolute law giver, absolute truth; the monotheism of ningun braham in hinduism with that of Judeo-Christian theology, the unborn and uncreated in buddhism and so on. You would look at the similarities in development of cultures from magical to heroic to transcendant…
A good example of method, and the primer of comparative religion, is Huston Smith's "The World's Religions."
This can teach students so much about their own religion and others and about truth and goodness and, how to discuss differences in religion without killing each other.
It would be quite a challenge for a middle-school level teacher (and students), I think High School would be better, and perhaps I'm being too optomistic in thinking it could be done justice short of the college level.
thanks for your reply.