Benevolent Psychosis is a Christian allegory. The "benevolent psychosis" is essentially the belief that God has a plan and it will all turn out okay in the end. This is in contrast to the less-mentioned "malevolent psychosis," which is essentially extreme narcissism and fear of death/anger at how the world is making the person think they know better than God.
Essentia is basically an avatar of Satan (called the God of Despair), and orchestrated everything in an attempt to avoid death by setting up ONISM to force the world to change by creating enough collective psychic force. It does not work, because obviously you cannot actually beat God, the idea is fundamentally delusional.
No seriously, that's legitimately what is going on. It has trinity imagery, Alex at the end is basically crucified, there's a grail full of blood, et cetera. That's why it mentions forgiveness, they specifically mean to say God can forgive even Alex.