Verses 1 and 2 give us the situation: Social outcasts, open sinners who were repenting, were listening to Jesus. But Pharisees and scribes, who were covert impenitent sinners, in their dissatisfaction and jealousy, were beginning to grumble at Jesus. In response Jesus spoke three parables. Jesus makes application in verses 7 and 10 but not in the parable of the Two Sons. The reader is left to find the point of comparison himself.
The word "repent" occurs in 7 and 10. Just as the lost sheep and the lost coin did nothing to be found, so "repent" must be understood monergistically, not synergistically. True, people repent but they do nothing which is meritorious before God. The word "repent" is not found in verses 11-32 but it is implicit in application of the younger son and is conspicuously absent in the elder son.
We follow Arndt's scheme of dividing verses 11-32 into five sections:
The Prodigal's longing for a life of sin. His request in verse 12 shows his insolent dissatisfaction with his freedom at home. Note the Father divided the estate, or the property, and gave shares not only to the younger but also to the elder son.
He loses his freedom and finds slavery and misery. This happened very soon. The younger son turned everything he had received into cash. He lived wildly. In verse 15 he becomes a slave. Feeding pigs was forbidden to Jews and here denotes utter degradation. "He longed to fill his stomach" might indicate that he had to be satisfied with what the pigs left. The verse ends with the man's utter destitution. He is friendless and no one cares about him.
His repentance. This is contrition. He had more than enough of this. He says: "I am dying!" "Against heaven" means against God. No excuses. Verse 19 indicates the humility of contrition but also the trust in the Father. Note the young son does not ask to be called a son.
Arndt: Here we have a picture of true repentance. But there is likewise faith in the father's forgiving love.
At the end of verse 21, unlike the KJV, the modern translations omit the last part of his speech according to the better texts. The father interrupted his son's speech. The stole, ring, and sandals indicate high honor. Look at Romans 5:20b, the last part.
Because of the father's compassion, the son gained more than he had lost. He received not his old robe back, but the father's best robe. Note the contrast between verses 15-16. The son goes from degradation to high honor. Ancient wealthy families always had a fatted calf on hand for special occasions.
Note the typical Hebrew parallelism in verse 24:
Note that the elder son does not address his father with respect, but merely says: "Look here!"
Verses 29-30 show that though the elder son had everything available to him, he speaks of himself as a slave, a man of self-righteousness, perfect obedience, a man who was not getting what was coming to him, a man who is extremely jealous of the person who has received mercy. It is a remarkable picture of the covert impenitent sinner, dissatisfied and jealous, who grumbles at the Lord. Furthermore, in verse 29b, he is practically saying that he never has a good time.
In verse 30 he refuses to speak of his brother but calls him "this son of yours." All he can do is find fault with his father. The mention of harlots is made without evidence but on the grounds of probability.
Note the contrast. The father shows affection for the elder son: "My dear son." The father shows not the least bit of anger and nothing has been withheld from the elder son.
Note how the doctrine of universal atonement or objective justification underlies this parable. God, in Christ, seriously and earnestly desires the salvation of all. He has done everything and says: "Come for all things are now ready." We would have expected the father to be angry with the elder son. But he is not. He divided his property with both sons in verse 12. Furthermore, in verse 31, though the elder son is angry, jealous, and very disrespectful, the father still says: "You are always with me and everything I have is yours." The heart of the elder son, of course, is not with his father but the father still loves him dearly. The only difference between the sons, in application, is that one repents, and the other does not. Compare the two malefactors in Luke 23:39-43
Geldenhuys: One well known commentator made this remark: 'Luke appears nowhere to associate the remission of sins directly with Christ's death.' This is not true. Luke's whole Gospel is framed and arranged in such a manner that it creates the impression that it has been written to illustrate the Pauline text: 'God commended His love toward us, in that, while we were yet sinners, Christ died for us. Romans 5:8.
On this whole passage compare 1 John 1:5-2:2. The angels sang at creation, Job 38:7; when Christ was born in Luke 2:13-14; and still do when one sinner repents, Luke 15:7-10. If the preacher cannot preach repentance, he can preach nothing.
The Christian sees himself in both of these sons. By the grace of God he repents and knows that, for Christ's sake, he is absolved. But he also sees the element of the elder son in himself. We need to repent even of our imperfect repentance.