Does one really require a belief in a deity to be brave? The answer to that question is the same as the answer to "Does one really require a belief in a deity to be moral?" And that answer is HELL NO!
There's even an organization of atheist war veterans, called the Military Association of Atheists and Freethinkers, who will gladly tell you about how they were atheists in foxholes.
Theists (or Christians, in particular) like to think that atheists deny God, that they know he exists, but just deny it because they are angry at him, perhaps over a horrible event in their lives, or maybe just to get attention. When faced with death, according the the Xians, they will repent and scream out to GAWD...this is really dopey. First of all, I'm not "angry at God." I just don't believe he's there...Christians may ask me why I act so bitter when he's mentioned...because I'm sick and tired of theists mentioning him. I'm getting sick and tired of Christians especially...I don't think I've ever met one that didn't despise me for who I am, even if they did try to hide it. My disbelief in a deity in spurred by logic, not hatred.
Secondly, if I did scream out to a god, which one would it be? Allah? Zeus? Zogfukus? Shiva? Ganesh? The fact is, I disbelieve in all deities equally...so it's very unlikely that I will scream out to God (ie, the Judeo-Christian god) when I die. No "God save me," no "Oh, Lord,". When faced with danger, the closest I usually come to saying any of those things is "Holy Shit!".
Everyone fears death to a certain extent, I don't care what they say. And religous beliefs, or a lack thereof, doesn't enter into it...