"Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me. Brethren, I do not count myself to have arrived; but one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, I press toward the goal for the prize of the upward call of God in Christ Jesus. Therefore let us, as many as are mature, have this attitude..." (Philippians 3:12-15).
Many years ago, when our son Brian was a small child, he came home from kindergarten and proudly announced, “I've learned how to snap and whistle. Now all I have to learn is to tie."
Snapping his fingers and whistling were important developmental tasks for Brian. When he learned to tie his shoes, he would have mastered all there is to know.
Some of us think that way: We know the doctrines of the Christian Faith and have our theologies ship shape, tied down, secure and squared away and thus have nothing left to learn. Contrary to Paul's attitude, we're "already perfected."
No, Paul would say. Christian maturity is not knowing stuff (that's Gnosticism), but knowing Jesus and becoming like Him in all that we think, do and say (Philippians 3:8-11), and not one of us has that "developmental task" squared away.
But we can "press" toward that goal, pursue it with all our mind, heart and will, and that attitude, Paul assures us, is "maturity" (3:15). Progress toward Christ-likeness and not perfection is the goal.