This is true. It is entirely possible he felt the Spirit at that other church's camp. The Spirit is no respect of denomination, IMO. It will testify of ANY Truth, where ever it is found, and many churches have some (or more) of it. Likely the camp activities revolved around Biblical lessons, and study, and that's certainly something that he'd find at the LDS church as well. But anyway, I agree with Ben. Have him read the Book of Mormon. That's probably the biggest source of Truth that he won't find at the other church. If you appear too much like you're trying to drag him away from that other church then you'll likely end up doing the opposite and pushing him to it.