[Always *]

I think it is very possible to date someone of a different faith to you as long as you are both open minded to each others beliefs. I think that there should never be an expectation to convert, ever.
However, like the poster said above me, to a lot of traditional families it would be extremely difficult to accept their child dating someone outside of the faith.
You wouldn't really know if it is something that would be a problem until you a guys actually got together. But religious/moral/cultural variances will either be a problem or they won't, it really depends WHAT the variances are.