In Luke 15, The Pharisees criticize Jesus for his welcoming and eating with sinners, and in response, Jesus begins discussing parables.
The first two parables (or hypothetical questions) follow the same pattern, showing that God (or Jesus) must value the lost part of the whole as much, or even more, than the whole itself; that it was only natural to throw a party when these lost ones were found.
He throws many of the same elements into the parable of the two sons, then contrasts the celebration with the elder son's disapproval, who shows the same attitude toward his father that the Pharisees show toward Jesus.
Further, Jesus attaches a bias to their actions through the story, contrasting the Father's unconditional love (receiving the younger son simply because he loved his son, without reference to his failings) with the elder son's desire to earn his father's good opinion (after all of his obedient works, he felt entitled to having a party with his peers to celebrate how good of a son he was). In this way, Jesus seems to show how much the Pharisees had failed to grasp who their God really was, and how different their priorities were from His.
He goes on tell his disciples a story (still in the hearing of the Pharisees, it seems from verse 14) where the punch line again is aimed at the Pharisees: the story seems to be directed at the interaction between faithfulness and the proper use of wealth.
Considering the parable of the rich man and Lazarus seems to follow this flow of thought almost perfectly, what part does Luke 16:16-18 play, sandwiched in between the parables as it is?
Luke 16:16-18, “The Law and the Prophets were proclaimed until John. Since that time, the good news of the kingdom of God is being preached, and everyone is forcing his way into it. It is easier for heaven and earth to disappear than for the least stroke of a pen to drop out of the Law. “Anyone who divorces his wife and marries another woman commits adultery, and the man who marries a divorced woman commits adultery.