Perfection and Purpose

If perfection is the fulfillment of one's being, or purpose, then evil, or imperfection is the failure to fulfill such a purpose. Evil is considered to be a corruption of being, of the good.

It can be argued that God is perfect because God is 'being itself' and God is the one being incapable of this corruption, incabale f tending towards nom-being.

So I think God is perfect not because He has a particular purpose to fulfill, but because His existence cannot be corrupted like ours can, He is infinitely perfect.

However, a problem for me arises when God commtis an action. There can be no concept of perfection prior to God, so God's action mustn't adhere to perfection, it must define perfection. However, a perfect action stems from a perfect will, but how can a perfect will exists if there is no prior concept of perfection?

From what I understand, the response to this is that 'God is act', meaning that there is no distinction between God's act and will. God is changless, there is no movement from thought to act, no movement from potentiality to actuality, they are one.