Our passage for study is made up of two teaching parables: The Lost Sheep and The Lost Coin, both of which are linked to the parable commonly known as The Prodigal Son, 15:11-32. Jesus has already made it clear that repentance is an urgent necessity - "unless you repent you too will all perish." In these two parables Jesus sets out to explain a substantial truth about repentance, namely that it is a particular human response toward God which fills him with joy, ie. it pleases him. This joy is the very same joy which Jesus exhibits when "tax collectors and sinners" gather around him.
 v1-2. Luke sets the scene by describing how the Pharisees and Scribes are offended by Jesus' association with people who are religious outcasts. These "sinners" were not the type of people "righteous" Pharisees and Scribes would want to include in their fellowship. The term "sinner" here describes those who do not keep the religious ceremonies dictated by the rabbis. They are therefore, unclean. "Tax collectors" were regarded as traitors because of their association with the Roman authorities. Jesus "welcomed" (received) them - welcomed their repentance, but not their sin.
v3-6. First, Jesus relates the parable of the lost sheep, or probably better, let's call it the parable of the seeking shepherd.
v7. Jesus now applies the parable. What pleases God, what fills him with joy, is the repentance of a broken sinner, the deliberate turning from self to God for mercy, for forgiveness, grace. God is not filled with joy at the compromised goodness of "the seemingly righteous", those who think they do not need to repent, think they "have no need of a physician." As Jesus said, "I have not come to call the righteous, but sinners to repentance", 11:31,32. So, a person's standing in the sight of God comes only through repentance. Only repentance prompts "rejoicing in heaven."
v8-9. The parable of the lost coin is a replay of the parable of the lost sheep. A woman, who has lost a coin, probably part of a piece of jewelry, searches for the coin, finds it and rejoices. The coin referred to in the parable is a "drachma", a small silver coin amounting to a day's wage for a poor person.
v10. Jesus now applies the parable in much the same way as he applied the parable of the lost sheep. What is it that pleases God, makes him happy? God is filled with joy when a person, who knows they are cursed in his sight, turns to him and asks for his forgiveness. Repentance brings joy to the Lord. As for "rejoicing in the presence of the angles", this means much the same as "rejoicing in heaven"; it describes God celebrating with the heavenly host.
 In the school playground we begin to learn the techniques of "how to win friends and influence them." There are two particularly unhealthy techniques which are often developed in later life:
First, there is the standover tactic: violence - "you be my friend or I'll pinch you." In later life the threat of physical violence is transferred to such things as guilt manipulation, the "put-down", vicious gossip....... A psychological manipulator maintains their friendships by the threat of harm. We tend to keep on the good side of such a person because we know they can do us damage; they can castrate us with a single word; they can destroy our circle of relationships. For such a person, even friendship itself is increasingly warped. Their desire for a meaningful relationship is replaced by the desire for power, control.... They become sad and lonely people.
Second there is the reward approach: bribery - "you be my friend and I'll give you a lolly". This approach seeks to please others so as to maintain, or develop friendships. In later life, the need to please others to secure friendships makes such a person a "doormat". The "user" quickly ferrets out the "pleaser" and uses them for their own advantage. The "pleaser" becomes the person who does everything for everyone.
Genuine friendships are not based on the need to manipulate, or to please. Genuine friendships develop out of mutual care and respect.
It is not hard to improperly picture God as a divine manipulator using a carrot and stick approach with us - the stick being the threat of judgment and the carrot his promised rewards. Of all the rewards, his good pleasure, his smile, is the most to be desired. It is often argued that one of the key motivators for godly behavior is God's good pleasure, the joy he feels when we act faithfully.
The trouble is "our righteousness is but filthy rags." The only righteous act capable of God's favour was the sacrifice of Jesus. There is nothing in our compromised life that is worthy of God's favor, for "even our most noble motivations cannot tolerate close inspection." Yet, when we turn to God for mercy, put our trust in Jesus for salvation, it is then that our God is filled with joy. Repentance is what prompts God's joy.
A believer has no need to try to please God, for in Christ our God is already pleased with us, and that completely.
 The quote, "even our most noble motivations will not tolerate close inspection", actually comes from a B grade movie titled The Henderson Monster. The movie was terrible, but the line is worth discussing!