At the club, none whatsoever. As for each individual student, mostly I have no idea. I think some people would say they are christians, some buddhist, some atheist, some have other views and believes. It has never been an issue in the dojo & never discussed on the mat. Not specifically excluded - just never come up as it is not seen as relevent to our training as a group.
In a previous dojo I did come across this as an issue personally, where we were studying ki aikido and my brother & wife considered the concepts we were talking about as against the teachings of Christ. We never managed to resolve this between us but it is not a major problem. Occassionally they comment that I am "learning how to fight" and I just reply "you mean learning how to not fight".