We are just exotic enough to make some of these skeptics accept us as an "eastern' religion and thereby unwittingly give Christianity another hearing.
That always seems to work for me
In response to your question, though, I would suggest talking to him in private.
Most people have never even heard of it, so when I bring it up to some insane History/English teacher, they sit down and shut about Christianity for the rest of the semester for fear of looking like a moron.
For example, my current English teacher (who is also an Episcopal priestess...) likes to lump all of Judeo-Christianity into one entity, preaching that all we care about is sin and damnation. Then she'll go off on a tangent such as: "What's very cool in Hinduism and Islam is that they teach about forgiveness and repentance."
For one, who the heck says "Very cool" in a semi-formal lecture when they're 45? And second, when has Islam shown to be a religion of forgiveness?
In her eyes, you're either a corrupt Catholic who pays for absolution of sins, or a snake-handling Evangelical wacko in the Bible Belt. I've been slowly introducing Orthodoxy into my writing pieces, yet she hasn't really caught on. I think I might have to have a private discussion with her soon, as well.