Devotion to Divine Mercy can be expressed notably through the veneration of the picture of the Merciful Christ, showing his open side, whence spring out two rays of light, a symbol for the Blood that increases the life in souls, and the Water which purifies the souls.
"Our Lord, complaining about a lack of confidence in his Mercy from the souls, requested that one adds the invocation: Jesus I put my trust in Thee".

"My heart suffers, for even consecrated souls ignore my Mercy and treat me with defiance. Oh, how much do they wound me! If you do not believe in my words, at least, believe in my Wounds."
(Our Lord to Saint Mary Faustina)

In all his Messages, our Lord, through his little secretary, makes us understand how he is fast in forgiving the souls who humble themselves, whatever may be their sins, whatever their grievousness. He is ever ready to forgive. His Heart being all love, he thirsts to be loved, and therefore this lack of trust causes him atrocious suffering, especially when it comes from the consecrated.

Our Lord and the Most Blessed Virgin Mary manifested themselves to her during 13 years of a hidden, painful life, to transmit her the message of Divine Mercy. Long conversation when the little Secretary had to note every thing, at the price of many sufferings, humiliations and persecutions.