What is the proper way to teach religion and which religion?
First start with the law of supply and demand. Where is the interest, especially since it would be an elective class. Then introduce the language, culture, history, and science of the time being studied. What they knew then...what we know now. Emphasize perspectives changed over time, one of the main ones being our own perspective of separation of Church and State as opposed to Church and State being one. Talk about how children were taught back in the day--not with texts, chrome books, and well researched news articles--but with stories. How do we find the lesson and the facts in the story. What is it that makes the lesson and the facts interesting and memorable? How does science explain some of the "Just So" stories today?
Explain philosophy and how it differs from science.
I recommend stop trying to pigeon hole religion/philosophy in such a way that it invites jeering and scoffing. Teach it correctly. Think of it in terms of a political party. Do we insist that students emerge from their government/history classes believing in a single political party, or do we simply teach and allow them, at some point, to make up their own minds--which may include not paying any attention to government and elections at all?
I do not understand the hysteria over teaching religion/philosophy.