You really get altered states that are more like trance when you go to pentecostal religions– loud music, speaking in tongues, wild emotions.

For just standard Christian prayer, like the Lord’s prayer or prayers asking for stuff, I doubt they take long enough to really be like hypnosis.

However, there is a line of meditation in Christianity that’s a lot like Buddhist meditation. It’s called "apophatic" meditation and was revived in the 70s by a monk name Thomas Keating. It’s all about letting the mind go… which reminds me of hypnosis. I don’t know a lot about it, but I think that the techniques they use for mental self-control are probably a lot like the same ones in self-hypnosis.
References :
http://www.hypnotizeyourselftoday.com/how-to
http://en.wikipedia.org/wiki/Trance
http://www.contemplativeoutreach.org/site/PageServer?pagename=about_people_keating

When you think about it, that’s all a worship service is.
References :

Lies and slander, I’d say. They hypnotized themselves and/or had been hypnotized by other people to think that way.
References :