Subsidiary post: The Process of Perfection
We use the word perfect in at least a couple of different ways. We use it as an adjective to say that something is without flaw of any kind; we also use it as a verb to describe how something is matured to completeness. It is in this latter sense, generally speaking, that the Bible uses the word.
Therefore, it’s less a matter of our becoming perfect and more a matter of our become perfected. For this reason, it is a process.