What I learned from the Prophecy (SPOILERS)
An angel can serve God unquestioningly, fight bravely, remain loyal through centuries of war even though he's not sure why he's fighting, risk his own immortality to come to Earth and try and save everyone from total chaos, resist the temptation to switch sides even when staring a hideous death in the face, and then get burned alive, and left in that state for an unspecified length of time before having his heart ripped out. And the revelation later in the film that angels don't have souls strongly suggests that the poor guy doesn't even have an afterlife to look forward to.
I'm still not sure what Gregory Widen was trying to say with this film: That Simon is commendable for his adherence to the side of good when there is nothing in it for him, or that he is a complete mug for the same reason.
Likewise, the emergence of Lucifer as the dominant (and sole surviving) angel character at the end was problematic. Are we meant to view him as being heroic for assisting in Gabriel's defeat even though, by his own admission, he does so for entirely selfish reasons? Gabriel is an unpleasant character, and it's hard not to cheer the person who puts a stop to his plans ("my enemy's enemy is my friend") but the fact that the instrument of Heaven and humanity's deliverance is the Devil himself raises another question: Is the writer showing us that God can use anyone to carry out His plans, no matter how corrupt they are, or is God, in this story, helpless to do anything but step aside and leave it to someone else to save His creation when it comes under threat? The unleashing of God's power at the film's climax would seem to suggest that He is far from impotent, but then why doesn't He just strike Gabriel with lightning in the first place and be done with it?