God loves us — all of us. And, he wants us to recognize that His mercy is greater than our sins, so that we will call upon Him with trust, receive His mercy, and let it flow through us to others. Thus, all will come to share His joy.
Ask for His Mercy. God wants us to approach Him in prayer constantly, repenting of our sins and asking Him to pour His mercy out upon us and upon the whole world.
Be merciful. God wants us to receive His mercy and let it flow through us to others. He wants us to extend love and forgiveness to others just as He does to us.
Completely trust in Jesus. God wants us to know that the graces of His mercy are dependent upon our trust. The more we trust in Jesus, the more we will receive.
Our Lord told Sister Faustina that He wanted this picture to be venerated and attached a promise to it:
"I promise that the soul that will venerate this picture will not perish. I further promise to that soul victory over enemies here on earth and especially in the hour of death. I myself, shall defend that soul as My own Glory...." I will preserve the cities and homes in which this image shall be venerated."