I agree with Trish's advice. I think school is a great place to learn a little about the world's religions. Human history has been greatly influenced by religion, for good or bad, and I think it's a necessary subject to know about. The school will not "force it down you child's throat" (geeze I dislike that phrase). I think it is quite mature of you to be prepared to discuss religion without bias. No one can make their mind up about something unless they understand it. I think some people believe that if they expose their kids to religion it will have an instant negative effect on them... like it's contagious or something. Happy to plonk little jonnhy infront of a violent teen gang movie but would cringe at little Johnny watching a Christian Easter movie. I also think raising kids is a little about removing fear and establishing comfort zones. My DH never when in a church until he was 22yo and so feels "uncomfortable" about doing so even today. I think mature people feel ok about every aspect of life as long as it isn't harmful. Is entering a church or synagogue or temple harmful? If you think it is then ok, your kids will pick up on that. I personally think that exposure and saying "this is ok for some people" creates more tolerant and resilient children and adults.
I'd go the school option, different religion per term. It will not scar them for life