What Makes Comics "Christian"?

I'm curious because I've had this discussion with pastors and youth pastors starting from way back years ago when I worked as a music buyer in a Christian bookstore. Of course, back then the discussion was about Christian music. What made it Christian?

The distributor?
The words?
The attitude of the artist's heart and his or her faith?
Was DC Talk Christian and Bruce Cockburn not?

Now I ask the same thing of Christian comics. What makes them Christian?

Is it that they're advertised and marketed as such?
Is it that they're published by Christian publishers?
Is it that they're blatantly evangelistic?
Or can mainstream comics written by Christians like Chuck Dixon and Roland Mann be included?
It is the attitude of the writer and/or artist's heart and faith?

Admittedly, I'm a bit liberal in my definition.

But I feel that almost any story, no matter the language or content (to a large degree) can be a story of redemption. Taking my cues from the Bible, it seems that almost no subject is taboo, from revenge, bloody wars, genocide, sex, incest, you name it. It's all in there, and I'm hoping that gives us earthly creators a grace-filled free reign to tackle almost any subject redemptively. 

I guess that's my definition at the heart. If it's a genuine redemptive story, it can be called a Christian one, because that's what Christ came to do, redeem.

But feel free to differ.