I think the big question on everybody's mind is, "What the hell is the 'Avenger', exactly? What will this class do that other classes don't?" We're all really curious; I know I am, because I'm genuinely not sure what it's about.
Is it a Paladin-lite? Is it a Rogue who prays before assassinating someone? Is it a "holy warlock"-type character, blasting foes with superpowered godlasers? "Divine" and "Striker" almost seem like an unnatural combination at times.
Many people have said the Monk would make a fine Divine Striker. Hell, Ari made the monk a divine striker in the Advanced Player's Guide. Divine is purely the explanation of the power source, and striker merely means "Mobile + Doing lots of damage + in trouble when alone against several enemies".
Now that I think about "Striker" and "Divine", I find myself imagining an Avenging Angel. An instrument of judgment, empowered with the wrath of their god to bring pain and punishment upon those that have wronged. One whom will track down the blasphemous offender to the ends of the Planes, and allowing nothing to get in its way.
Or, if you prefer: David slew Goliath with one shot.
Where the Paladin protects, or he single-handedly steps into a throng of an evil army, cutting a swath through it, or single-handedly battles a tide of onrushing demons, the Avenger goes straight to the heart of the matter, his holy sword piercing the source of the evil itself, such as the sorcerer who brought the Demons.
As I think about it, one method it could have is playing off doing damage to foes who have hurt party members. Similar to how the Paladin's mark damages foes who attacks the non-paladin, the Striker could do extra damage to those who have harmed their allies. Getting bonuses to damage when their allies are bloodied, and so on.