Although more Christian Rock. I myself am very much an atheist, but to find a Rock band which is religious, so the lyrics mean something, is beautiful, and i never grow tired to them.
Also songs from flyleaf such as 'Cassie' are probably the most impacting, certainly as it's a religious story based on a true story.
I have never heard any Christian heavy metal bands before. what are they like?
I'm not meaning to be offensive, but in my personal experience, there's no distinction. Most Christian Metal Bands write songs about the exact same stuff that metal bands do. I'm sure there are exceptions, but I've never heard a metal song about John 3:16 or a metal version of "Jesus Loves Me". The music they make is about their own perspectives on things that happen to them as they live their lives, or stuff that they feel strongly about.
Venom isn't black metal and their lyrics are just satanic. The bands I listed have satanic and/or anti christianity lyrics. I was just joking around with veobahamut.