We need to hear how, in fact, Luke starts chapter 15:
“Now the tax collectors and sinners were all drawing near to hear him. And the Pharisees and the scribes grumbled, saying, ‘This man receives sinners and eats with them’ (vv. 1-2).
“And when he comes home, he calls together his friends and his neighbors, saying to them, ‘Rejoice with me, for I have found my sheep that was lost’” (v. 6).
“And when she has found it, she calls together her friends and neighbors” (v. 9)
The wider narrative in Luke suggests that it is whom we invite to these “feasts” and times of “eating” that is at issue. For Luke 15 is bracketed by chapters/stories of "feasting" (i.e., "eating"). First, there is the parable about proper kingdom table etiquette (the inviting of the marginal and socially unacceptable) vs. the acceptable social norms (chapter 14) and, then in the preceding chapter, the story of a rich man, who “feasted sumptuously” and poor Lazarus, “who desired to be fed with what fell from the rich man's table” (16:20-21).
The lost-dead-prodigal-son isn’t just a picture of the wayward sinner, the lost law-breaker, but is a figure representing--to keep with Luke's theme--the socially unacceptable that are now welcome, equally, without hesitation or qualification (save faith) to God’s kingdom table.
These parables, including Luke 15's parable of the prodigal son, are forming for church and missional church-life. Luke 15 is one of the parables that scream out: “Go do likewise!” Who are you eating with? Who are you intentionally inviting and compelling to come be a part of your local church? Maybe even more so, who are you making second class citizens of the kingdom by how we do church?