When his pregnant wife is murdered, a grieving husband must kill the man responsible before joining her in the afterlife.

Sorry, just saw that you mentioned it's actually a comic. Still, without a hook it's a tired formula.

Poromaa's suggestion is good - the vengeance killing is the qualifier for the man's soul to pass onto the afterlife. If you've got something like that in there, it makes the story unique - gives it a hook. Without it, the film just sounds like a bog standard revenge flick.

Like mmckean says this logline lacks something. Nothing is at risk here since he will die even if he tries or not. Also he won't get her back revenging the murder? Not knowing your story I could come up with a new one that would put something at stake.

"When an african tribal priest pregnant wife gets killed, he must obey the gods by revenge the killing to secure a place with his beloved in the afterlife"

This sounds like an interesting idea but something is definitely missing here. Im re-reading it to try and figure out what it is.... I guess it just sounds a bit cheesy.... Ok, here is the thing I've noticed with it: The guy's pregnant wife is murdered, which is terrible, but he is already going to be joining her soon in the afterlife and that takes away from the 'cool' factor of the film. With vengeance films like this you want the viewers to say "jeez, I would totally want to annihilate that guy!!" so I would leave out the afterlife thing because it lessens that feeling a bit. Besides, he will surely see her in the afterlife anyways eventually, unless he is a demon or something.