The message of The Divine Mercy is simple. It is that 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. 

The Divine Mercy message is one we can call to mind simply by remembering ABC: 
A - Ask for His Mercy

B - Be merciful 

C - Completely trust in Jesus

 This message and devotion to Jesus as The Divine Mercy is based on the writings of Saint Faustina Kowalska, an uneducated Polish nun who, in obedience to her spiritual director, wrote a diary of about 600 pages recording the revelations she received about God's mercy. Even before her death in 1938, the devotion to The Divine Mercy had begun to spread. 

How to Recite the Chaplet