I was watching the countdown special on Spike TV last night for UFC 71. Quinton Jackson was not only funny but made a reference to his faith. After looking into it Jackson is a born again christian and makes it known in several of his interviews on UFC.com - Rampage Article

“I was just messing up. But it wasn’t me who decided it was enough; God was the one who did all this. Because I was still out there partying and a couple of days before I was born again. My friends thought I was going crazy. My family was very religious, I grew up in the church, and at first my mom thought I had did some drugs or something like that. So I broke it down to her. My mom was born again when I was younger, and I said, ‘well if you don’t think I can be born again just like you was, then you need to check your own faith.’ Then she understood and now we have a better relationship.” - 05/21/2007 Quinton’s Quotables By Thomas Gerbasi

Off hand the ones that I have heard or seen make reference to their faith latley are:

Ken Shamrock (In a special for IFL)
Diego Sanchez (He usually makes a shout out after every fight)
Josh Koscheck (He made a quick reference in an online video interview)
Pat Miletich (I saw him praying last night for his IFL team)

I am sure there at tons of other fighters out there that are chrisitans too and it is nice finding out.