My Interpretation (SPOILERS)

Ottway (Neeson) is in a horrible state of grief after the passing of his beloved wife as he protects oil workers by shooting wolves that get too close to the camp. Depressed, he decides to commit suicide but before he can pull the trigger a wolf howling in the distance strangely prevents him. I believe the howling wolf was the Creator's way of speaking to Ottway and giving him a chance to go out fighting; and not just that, go out believing as well, even if it's belief in its rawest form.

The next day Ottway finds himself surviving a plane crash in the wilderness with six other men. In contrast to his near-suicide attempt, his survival instincts kick-in and he finds himself doing everything he can to survive, for himself and the others. Do you see the irony? The night before he desperately wanted to die and a mere day later he's doing everything in his power to live and save others.

The topic of God and faith comes up at a campfire. A couple of the guys believe, but Diaz naturally mocks such things. Ottway says he doesn't believe either, but he wishes he could.

Later in the story, Ottway finds himself the sole survivor and at the end of his rope. Cursing, he passionately cries out to the Almighty for succor, but the heavens remain mysteriously silent. Regardless, he musters the strength to (try to) carry on. Shortly later, while reflecting on the men and their loved ones who died, he seems to clasp his hands in prayer and the Alpha wolf appears and challenges him. Unlike a few days ago when he was going to kill himself, he goes out fighting and, even more important, believing.

For those who argue that Ottway didn't believe, remember that he was praying when he was crying out to God. Yes, it was a prayer of desperation and rage, but prayer nevertheless. Job did the same thing in the bible. The utterly humbling situation drove Ottway TO his Creator and compelled him to go out fighting. It was God's gift. The Almighty knew Ottway better than Ottway knew himself.