Those who are well do not need a physician, but the sick do.
Go and learn the meaning of the words,
I desire mercy, not sacrifice.
I did not come to call the righteous but sinners.
When I was a boy we had back door friends and front door friends. The front door was for formal visits and strangers. They should see the best side of the house and the better rooms: the living room, bathroom and dining room. These were ready for guests. They, in turn, were expected to knock before entering and leave before late. They should dress properly, at least clean and neat, not coming straight from work.
The backdoor was for close friends and family who might come in without knocking, who could make themselves at home without formality. They knew our poverty without pretension; they knew we had misunderstandings, quarrels and, sometimes, violence. They also knew when to leave without excuse or apology.
Jesus comes into our lives through the backdoor. He might abide a formal entry for a while but he's not impressed by pretense. If our formal friends see what we'd rather not discuss, Jesus can be quite frank. He will observe and ask about the bad habits, the surly attitudes and the unnamed issues. He will also reassure us that he has seen it all and there is nothing to be ashamed of. When we're ready to laugh about our misdeeds and mistakes he will laugh with us.
He invites his Christians to know one another as back door guests. We need no pretensions among us because, with our very entrance into the church we admit we are sinners and cannot save ourselves. We came, after all, in through the backdoors of Baptism and Penance.
Being family, we can tell stories about ourselves and listen without judgement to others' stories. They only remind us again and again of God's gracious goodness; he has made us at home in his house.