This confuses me. Lucifer was once on the side of God before he rebelled right?
So we're told.
Then he rebelled, was cast down, became evil, etc., etc. If the devil was once good before his really bad decision, how can he be pure evil? He was good before he was evil.
It's to do with how the Tradition understands the distinctions between corporeal nature, like ourselves, and incorporeal nature, as per angels.
Dionysius says:
... those (angelic) Natures which are around the Godhead have participated of It in manifold ways. ... (Angels) are present with and participate in the Divine Principle in a degree far surpassing all those things which merely exist (matter), and irrational living creatures (flora and fauna), and rational human beings (man). For moulding themselves intelligibly to the imitation of God, and looking in a supermundane way to the Likeness of the Supreme Deity ... they naturally have more abundant communion with Him ... and they receive the Primal Radiance in a pure and immaterial manner, adapting themselves to this in a life wholly intellectual.
This last, 'a life wholly intellectual' encompasses the ancient philosophy that the Intellect is transcendent in that it is a participation in the Divine Intellect. They did not understand 'intellect' the way we moderns understand it, as someone who is clever, who knows a lot, is sophisticated, etc.
But the point is, humans are bi-natured, the union of intellect and matter, whereas angels are pure intellect.
When man fell, the sin was from outside in, as it were, the whole story is one of the seduction of the (physical) senses over-riding the (mental or common )sense that would have said, 'If God says don't do it, don't do it'.'
But the angelic fall was different, because they are creatures of pure spirit/pure intellect, theirs is a more immediate participation in the Divine, they do not see 'through a glass' as we do ... their knowledge is not reflected in the mirror of the soul, but is a direct and immediate knowing, and in that sense they are creatures of light.
In the Bible it's evident that God withdrew His grace from man when man transgressed. When the angel transgressed, he corrupted his capacity to receive/participate in Divine Being by the corruption of his own inherent nature. It's given then that man is essentially good, wounded by sin, and in need of Divine assistance to work his salvation. The angels however, became in essence creatures of sin, or the idea that forms the core of their being is a contrariness, so in the sense the angels cannot repent because they cannot go against their own nature.
God could heal the angels, and perhaps He does, but that would be a miracle, and not for us to say.
Also, as angels are 'outside' time, the Fathers grappled with the question of when did the angelic fall happen, and there is a stream of thought (Aquinas) that it was simultaneous with their creation – not that they were created fallen, nor predestined to fall, but exercised that option, as it were. St Basil believed in a spiritual creation prior to a physical creation, but again as this spiritual creation is not governed by time, we can say prior, but not before, if you get my drift.
Lastly, there is also the teaching that Christ came to redeem man, and the whole things turns on 'Father, forgive them, they know not what they do'. He never said anything about angels, and they knew what they were doing.
