I'd heard List was a Lutheran, but don't recall hearing which church he belonged to.
And I'm not sure he's properly classified as a serial killer. He murdered his family, but I don't recall his ever having killed anyone else. While this qualifies as a miltiple murderer, I don't believe this qualifies as the serial type.
Also, he was on the run for a number of years. What I know comes from an old TV program so may not be that accurate.
OTOH, John Wesley Hardin was a Methodist, I believe (note the first and middle names). He was one of the most prolific killers of the 19th Century. What does that tell us about Methodists (just kidding, folks...)?
I think you're right. Still not a good thing, though. :-)