The Father knew he’d be back. He was even looking for him a long way off on the day he returned.
The father saw his son returning. It says nothing of him "looking for him."
The decision was the son's, period.
Luke 15:
17
Coming to his senses he thought, ‘How many of my father’s hired workers have more than enough food to eat, but here am I, dying from hunger.
18
I shall get up and go to my father and I shall say to him, “Father, I have sinned against heaven and against you.
19
I no longer deserve to be called your son; treat me as you would treat one of your hired workers.”’
20
So he got up and went back to his father. While he was still a long way off, his father caught sight of him, and was filled with compassion. He ran to his son, embraced him and kissed him.
21
His son said to him, ‘Father, I have sinned against heaven and against you; I no longer deserve to be called your son.’
It says that he caught sight of him a long way off. It mostly certainly does not say that he was looking for him. It DOES say that the prodigal son was welcomed back AFTER he repented. Not before.
Now, let us recognize frankly at the outset, that the reason why these new teachers of an unchristian Christianity do not find Christianity in the parable of the lost son is, briefly, because this parable does not set forth Christianity, but only a small fragment of Christian teaching. The turn they have given to affairs is therefore merely the nemesis that treads on the heels of the mistaken attempts to read a full Christianity into this parable. The parable was not given to teach us Christianity, in its essence or its sum. It was given to teach us one single truth: a truth of the utmost value, not only full of emotional power, but, when placed in its relation to other truths, of the highest doctrinal significance; but not in itself sufficient to constitute Christianity, or even to embody its essence. How little what this parable teaches us can be conceived as of itself Christianity may easily be made plain by simply enumerating some of the fundamental elements of Christianity which receive no expression in it: and this negative task seems to be made incumbent on us at the outset of any study of the parable by the circumstance of its perversion to the uses of the propaganda of unbelief. We observe, then, in the first place, that there is no atonement in this parable. And indeed it is precisely because there is no atonement in this parable that it has been seized upon by the modern tendency to which we have alluded, as the norm of the only Christianity it will profess. For nothing is more characteristic of this new type of Christianity than that it knows and will know nothing of an atonement. The old Socinians were quick to perceive this feature of the parable, and to make use of it in their assault upon the doctrine of Christ's satisfaction for sin. See, they cried, the father in the parable asks no satisfaction before he will receive back his son: he rather sees him afar off and runs to meet him and gives him a free and royal welcome. The response is no doubt just that other Scriptures clearly teach the atonement of which no hint is given here; and that we have no "right to expect that every passage in Scripture, and least of all these parables, which exist under necessary limitations in their power of setting forth the truth, shall contain the whole circle of Christian doctrine." This answer is sufficient against the Socinian who appealed to Scripture as a whole and required to be reminded that we "must consider not what one Scripture says, but what all." But it scarcely avails against our modern enthusiast who either professedly or practically would fain make this parable the embodiment of all the Christianity he will profess. For him, Christianity must do without an atonement, because it is quite obvious that there is no atonement in this parable. Nor is that more than the beginning of the matter. It must do without a Christ as well. For, we must observe, the parable has as little of Christ in it as it has of an atonement..." "...For the exaggerated estimate which has been put upon this parable has borne bitter fruit in the world. Beginning with an effort to read into it all the Gospel, or at least the essence of the Gospel, it has ended by reading out of the Gospel all that is not in the parable. And thus this parable, the vehicle of a priceless message, has been transformed into the instrument of a great wrong. The worst things are often the corruption of the best: and the attempt to make the parable of the lost son the norm of the Gospel has resulted, I will not say merely in the curtailment of the Gospel, — I will say rather in the evisceration of the Gospel. On this platform there take their stand today a growing multitude the entire tendency and effect of all of whose efforts it is to eliminate from Christianity all that gives it value in the world, all that makes it that religion which has saved the world, and to- reduce it to the level of a merely natural religion. "The Christianity of the prodigal son is enough for us," they declare: and they declare this with gusto because, to put it briefly, they do not like the Christianity of the Bible or the Christianity of Christ, and are happy not to find them in the parable of the lost son.