When I was in undergrad, there was a friend of some friends who was interested in Christianity, but who believed that God/Christ being ‘the same yesterday, today, and forever’ and being perfect would mean that God could not act. Sameness, he argued, implied stasis; God cannot be a dynamic being if He is the same, but, rather, a static one. So God can’t do things, because doing things implies changing.
However, God is perfect, so He is perfectum, which means he is complete and lacks nothing. If we consider this idea in terms of fulfilling your our purpose or (since God is self-sufficient) being eminently what you are by nature or essence (ontologically), then we see that God can act and still be perfect; indeed, perhaps if God did not act, he would be imperfect. If perfection implies being what you are at its fullest, and God is love, then perfection would logically mean that God acts, but that none of his acts are imperfect. He loves perfectly.
He also, as I’ve argued here before, loves infinitely.
From this question, let us ask another. How can we fulfil Jesus’ command to be perfect as the heavenly Father is perfect? (Mt. 5:48) Or how do we understand Hebrews 10:14, where it is said, ‘by one sacrifice he [Christ] has made perfect forever those who are being made holy’? What does it mean when we think on heaven/paradise, where there seems to be an expectation that there will no longer be sin? Does this mean we sit around doing nothing?
By no means! In fact, it doesn’t even mean that we will have no room for growth and development. St Gregory of Sinai (c. 1260-1346) says:
It is said that in the life to come the angels and saints ever increase in gifts of grace and never abate their longing for further blessings. No lapse or veering from virtue to vice takes place in that life. –Philokalia, volume 4, p 222
The idea here is one that goes back at least to St Gregory of Nyssa (335-394) who discussed in The Life of Moses that since God is infinitely good, then we finite beings will never stop progressing in goodness. It is an interesting idea. Perfection for the finite means progress (true progress) in holiness, in becoming more like God (that is, theosis).
As far as this life is concerned, we must realise that we can always be holier, even if we are less sinful than we used to be. Our finite state of goodness is not simply marred by sin but limited by its own nature. St Athanasius (296-373) expresses the idea that Adam and Eve would have progressed in knowledge and maturity and holiness of a divine sort even if they hadn’t disobeyed in the Garden (see On the Incarnation).
Even the angels progress in grace.
This is what a better understanding of infinity and finitude can do for us. Ever upwards!