Jack is a keen webcomic written by David Hopkins, and is readable at http://jack.keenspace.com/. The characters are furries, but that's not what the comic is about.
Instead it's about Hell, and the damned souls who are there. Sometimes angels from Heaven appear, and sometimes a character is still alive, but often they die in the course of the story.
As of yet, neither God or Satan have appeared as characters, or even been directly mentioned, which is a good thing, because then the story would be about them, and that would not be interesting. There are not any actual demons either. Every soul in Hell was once alive. We don't know if the angels were once alive, though.
The title character, Jack, is in Hell because of his sin, wrath. In fact, he was so full of wrath when he died that that is now his title, "The Sin of Wrath". Jack is a nice guy and a crusty ol' softy, but don't make him angry. Some of the other Sins in Hell are Lust and Gluttony. Jack doesn't like them.
And with his title, he also has a job. He harvests the souls of mortals when they die. Sometimes he has to chase them. He then takes the soul to either Hell or Heaven. Jack is not allowed to visit Heaven, but a has a friend who is an angel, who comes to visit him sometimes.
The art and stories are often very grim and gruesome. Hell is not a nice place. It's not nice because the things that souls do to each other, both in Hell and while alive, are not nice. Some people are insane. Some people are just evil. People murder, and torture, and rape other people.
But people can love, too.