In the gospel reading, Jesus addresses a parable: ‘To some who were confident of their own (!) righteousness and looked down on everyone else.’ The Pharisee is confident of his visible righteous. He looks at the sinners around him. The tax collector standing afar beats his breast and declares ‘God, have mercy on me, a sinner.’ He does not look at the sin of others but knows his own sin. Jesus declares that the tax collector is ‘justified before God.’
The gospel is the message that sinners are justified by God through Jesus Christ. So, all those who are burdened by sin can cry out ‘God, have mercy on me a, sinner.’ To be sure, at your baptism your sins are forgiven and you are made into a new person. However, the sinner remains.
Christians are thus simul justus et peccator (sinner and saint). For this reason, we continue to cry out ‘God, have mercy on me a, sinner.’ When we use these words, Christ gives you the faith you received at your baptism. He says ‘My child in me you are justified! Live from your justification.’ And so, living from your justification means that you have comfort before God. And then you are freed anew to love, praise, call, worship, and thank God.