Read the Bible. Take into account how Jesus DIDN'T belong, how His struggle makes sense for Christians to also find it hard to belong, seeing as our strong moral standing and heightened sense of right makes us disliked in present (and past) society. Talk about how Jesus warned against this, and His assurance that we are a family, belonging to each other.
If you need more specific stuff, look into marriage and sex.
If you don't know a good book to read, try Mark. It's the shortest of the gospels.
All the best!