What should I say my friend, when he can't decide, what religion he should believe?

Honestly if I was in your shoes the first thing I'd tell 说 friend is: I can't help 你 choose a religion. It is up to 你 to develop an independent mind and figure out what do 你 truly believe in. And 你 shouldn't allow anyone including me tell what to believe 或者 not believe. if 你 choose to be an atheist 或者 something out of the choices you've listed already. It would be still your choice first and foremost.

And that would be the 建议 I'd give them. I believe strongly in the right to think independently. Things like religion isn't something 你 decide based on advice. It's something 你 decide based on your own opinion and what 你 truly believe in. if she can't think I'll suggest her to read 图书 based on both religions constantly to get a better idea about them.

I would say, "I'm sorry. I can't help 你 decide what religion to follow. That's something 你 decide on your own. Besides, 你 shouldn't rush. 你 don't have to choose a religion at eighteen. 你 don't even have to choose one at all. Not everyone follows a religion."

Why does she even have to choose she can believe in both if she wants to.

I'm not sure about Buddhism, but I know that with the different sects of Christianity, she has many people she could talk to, Bibles to read, and information based on the Bible. I know in this area (and many places) the Jehovah Witnesses would be happy to do a Bible study with her - in her own 首页 或者 a place that she would like to study.

After she has enough information on the religions - she could make a decision for herself. I guess the best 建议 I could give is to look into the two religions she has to choose from, and then make her own decision.