This famous last saying of Jesus right before He died requires some explanation. The term in Greek daily use indicates a bill had been paid in full. But there the translation falters, because one can always incur a new bill. Not so with God. When He said it is finished He meant forever. We are wrong to think that life is ahead of us. In actual fact we are walking out the program of God.
Compare this to a toy train. If it is going too fast or meets an obstruction, it jumps the track and the little wheels on top of the train keep spinning until we right the train back on the track. That is our lives. We get off track and have to right ourselves, but the train track doesn’t change direction. We have this notion that God is thinking up ways to make us miserable, or to discipline us. Not so. He is only interested in the track.
Now if we make a deliberate rejection of his plans, we jump the track. It may be some time before we get back on the track, but we will, eventually. He does not determine our sins; He merely recognizes them and waits for us to right ourselves. The track for our life is the “tetelestai” and our obedience puts us on the track – or not as the case may be. We are not living day-to-day. All of life is nothing more than living in His plan.