If you know each other to push and push, then I guess that's fine. I just know from experience that if you push, push, push, it can push the person away *shrug* I personaly hate being pushed / nagged about something.
I don't think getting him into the Krismas spirit is being pushy in a bad way with him. If he was resistant because it bothered his conscience, then yes, getting him into the spirit wouldn't really be that nice to do. However, it is more about him not being used to it more then anything... Getting him into the spirit of something he's simply not used to but seems to be enjoying, is not being pushy in a way that would cause offense at all.
Oh, and we definately don't nag eachother.