Why do some christians go overboard, as in crazy, when it comes to there religion?

i met a girl who invited me to her church a new age evangelical christian type of place. i couldnt help but think to myself "are these people all nutjobs or what?" there was a part when they all started preying in tongues and making there kids do it, thats when it became disturbing to me. as an outsider obviously this appears to be a gathering of mental patients. are there any proclaimed new age christians out there that do this just to fit in? or some one explain to me why you do all the crazy stuff instead of conventional church stuff?