Jesus shares the parable of the lost coin (Luke 15:8-10) in connection with other parables on the lost (the lost sheep and the prodigal son). On one hand, the parable illustrates why Jesus chases after the sinner who is willing to repent and on the other hand, the parable is meant to help us identify ourselves as sinners and repent.  Repentance is a Kingdom Key and true repentance means actively working on eliminating the sin.  The reason why Jesus sat with sinners was because there was a willingness to listen, learn and repent amongst the sinners.  The Pharisee were too busy judging instead of seeing Jesus' actions as a kingdom pathway for all, including themselves.  We are all works in progress and seeing both sides of the coin is wisdom. There is enough grace for us all and access to it comes through repentance.