Cowardice? No. You have to remember that to the kind of people who really believe in an angry god, being afraid of God's wrath is just as logical as being afraid of falling, or being hit by lightning, or anything else of that nature. We don't generally consider people cowards because they take actions to avoid being hit by lightning, nor do we consider people cowards because they take precautions to keep from falling. So, too, taking precautions to avoid God's wrath (if one believes it to be real) is not cowardice.
As to the other kind, the ones who are afraid of death meaning oblivion, I also don't consider this cowardice. The concept of death, that one will someday no longer exist, is arguably the most terrifying thing for anyone to consider. The concept of heaven may well be a coping mechanism to deal with this otherwise crippling terror. Cowardice is not being afraid of something, cowardice is running away from the fear. Trying to deal with something that's scary, even if it's in a way that's nonsensical, is not the act of a coward.