What does Luke 15:30 mean?

Scripture doesn't give one single motive for the older son's anger (Luke 15:25–28). It may be because he toiled for his father's estate for years while his brother was shamefully spending his inheritance (Luke 15:11–13). Perhaps it's because the father has killed an expensive, reserved animal for his brother but never thought to give him a goat to enjoy with his friends (Luke 15:29). Or it may be because the father so readily accepted the younger brother back and so easily dismissed his dishonorable actions (Luke 15:11–29). Likely, it's all these complaints and more. In short, the older son feels that the father has rewarded the wrong son.

What the older brother fails to see is that the father considers him closer than he realizes. He is not slaving for his father's estate; he is building his own. The father didn't kill the fatted calf for his younger son; he killed it for himself—and the older brother—to celebrate their family's restoration. The older brother uses "this son of yours," denying all personal connection. The father wants him to see that the brother's return is a blessing for the whole family, which the older son will one day lead (Luke 15:31).

Jesus sees the same attitude in the Pharisees and scribes who criticize Him for eating with tax collectors and sinners (Luke 15:1–2). They don't see that the repentance of sinful Jews and their restoration to their heavenly Father is a win for all Jews. Their territorial display is not helpful. It's no wonder the Pharisees who become Christians have a difficult time accepting Gentiles into the church (Acts 15).