Yeah, there are a lot of bands which aren’t classified as “Christian” but who seem Christians nonetheless. I have wondered if Coldplay - or, at least, lyricist Chris Martin - isn’t a residual Christian lyricist since he does write about some spiritual topics, including the fact they have a wonderful song called “Moses.”
What worries me, personally, are the bands who might claim to be Christian in order to appeal to a certain niche market, but whose lyrics aren’t Christian. I know there is still a lot of debate concerning the hard-rock band Chevelle, who signed to a Christian label but has also toured on Ozzfest and whose albums also contain some profanity. This shouldn’t be a worry for those of us who are old enough to determine what constitutes sound Christian lyrics and what doesn’t, but what about the younger audience?
As far as Creed, I’m not sure if they are Christian or not, but they do have some very spiritual lyrics. However, I know there’s a lot of scandal surrounding the actual band. You can read about some of these on wikipedia. They definitely seemed to have the message, but it appears they needed to work on witness. Don’t we all, though?