Okay, I love this movie, but...

Here's the way I see it:

All of Prior's visions of the angel and what the angel told him run parallel to (or are the embodiment of, if you believe them to be nothing but hallucinations) his feelings of fear and uncertainty to live in the face of impending death. And it's not just Prior's death, but the death of many of his friends. Remember that in 1985, there was no treatment for AIDS, and it was a veritable death sentence.

So Prior is given this death sentence, and his lover leaves him to die alone. In the meantime, an angel visits him and tells him that he and the rest of humanity must stop moving forward. Not only does human progress and evolution (or in the eyes of Regan era neo-conservatives, immoral devolution) cause pain, but it also has intrigued God to the point that God got bored of his angels and left them.

Essentially, the angel is asking Prior and all of humanity to stop living and stay perfectly still. This will stop the pain (and arguably the spread of human disease), and bring God back to heaven. But Prior is arguing that just because he's sick, and just because pockets of humanity are self-destructive, that doesn't mean that life isn't still worth living and fighting for. Human life, for all its frailties and imperfections, is still something that he wants.

The evolution of human life is an interesting concept in the 1980s, in light of what neo-conservatives considered to be the end to moral bankruptcy with the rise of President Regan. Thousands of people were dying from an insurmountable disease that went ignored because it was perceived as a disease that only gay people, or immoral people, contracted. But people like Prior refuse to give up on life, and they refuse to be ignored anymore.

Also keep in mind that Mother Pitt saw the angel as well. You had Harper having her vision as well meeting Prior and being told by him that Joe was gay. Before that moment she never considered he was gay. This movie had so many layers.

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