[These] expressions “to redeem,” “that we might receive adoption,” “you are sons,” “He has sent the Spirit,” “He is a son and heir, not a slave,” and similar expression are not to be understood as having been fulfilled in us, but that Christ has fulfilled this in order that it may also be fulfilled in us; for they have all been begun in such a way that from day to day they are achieved more and more. For this reason it is also called the Passover of the Lord, that is, a passing through (Ex. 12:11-12), and we are called Galileans, that is, wanderers, because we are continually going forth from Egypt through the desert, that is, through the way of cross and suffering to the Land of Promise. We have been redeemed, and we are being redeemed continually. We have received adoption and are still receiving it. We have been made sons of God, and we are and shall be sons. The Spirit has been sent, is being sent, and will be sent. We learn, and we shall learn.
And so you must not imagine that the Christian’s life is a standing still and a state of rest. No, it is a passing over and a progress from vices to virtue, from clarity to clarity, from virtue to virtue. And those who have not been en route you should not consider Christians either.
Luther, Martin Luther’s Works: Volume 27: Lectures on Galatians 289