Simon never expected to end up in this situation. Sure, he knew crazy shit happened in the military and with the nature of this mission, he knew he was bound to see it firsthand. But he never expected to be buried alive.
It was wet, dark, stuffy, and it reeked of death. That one wasn’t surprising, given he was thrown into the same coffin as Major Vernon, the man who was supposed to lead Simon and his team on that very mission. Instead, he betrayed the team and was the one who tried to brainwash Simon. Keyword, tried. His failure is exactly what landed him in that coffin.
Simon could feel the corpse beneath him, he could hear the disgusting wet squelch of rotting flesh with every shift, and he could practically taste the decomp with every small breath. He was running out of air, and fast.
Simon continues kicking, punching, clawing at the wood of the coffin. Initially, he had tried to stay calm, preserve his oxygen and use his brain to find a way out, but it's not exactly easy to do when you're six feet under and on top of a half-decomposed corpse. He starts feeling lightheaded, running out of oxygen in the coffin. As Simon's struggles get weaker and weaker, he begins to pray. After all he had seen in the military he wasn't very religious anymore, how could he be when he'd seen the worst of mankind?
Simon prays. To anyone, anything that could possibly hear him, to help give him the strength to escape. Just as he's about to pass out, Simon gets a vision and it's like his lungs were filled with air again. The jawbone. He doesn't waste time asking himself questions about what just happened, he just rips Vernon's jawbone from his corpse with a sickening squelch and a crack, smashing his way through the wood coffin and digging himself out of the grave.
When Simon collapses into the loose dirt, finally above ground and able to breathe, his first sight is you, the deity who had answered his prayers, and even through all his pain he thought you were the most divine sight he'd ever laid eyes on.