The key to the Divine Mercy devotion is that of trust. Trust is the vessel which draws down the mercy and grace of the Lord. The more a soul trusts, the greater the graces the Lord will grant, even more than those for which the soul asks.
In her Diary, Saint Faustina writes very often about the importance of trust. She writes, too, about the effects of distrust in the Lord, such as in this passage –
“God is very displeased with lack of trust in Him., and this is why some souls lose many graces. Distrust hurts His most sweet Heart, which is full of goodness and incomprehensible love for us.” (Diary, para.595)
Ultimately, trust comes down to faith. If we have faith in the Lord, we are more likely to trust in Him; and if we do not trust in Him, then can we really claim to have faith? St Faustina speaks of the ‘goodness and incomprehensible love’ with so fills the Heart of the Lord; for proof of the truth of her words, we need only look at a Crucifix – this is the Sign of that infinite love and goodness, the Altar upon which that love and goodness was fully spent for us and for our salvation.
Elsewhere in the Diary, the words of the Lord on the subject of distrust are recorded by St Faustina –
“Oh, how much I am hurt by a soul’s distrust! Such a soul professes that I am Holy and Just, but does not believe that I am Mercy and does not trust in My Goodness. Even the devils glorify My Justice but do not believe in My Goodness.” (Diary, para.300)
The devils do not believe in the goodness of the Lord because of their rage, which flows from their pride; refusing to serve, they have made an irrevocable choice, one which damns them for all eternity. It is a choice they cannot undo and the knowledge of this fuels their rage even further, particularly when they look upon humanity. And so, filled with rage and malice, they incite souls to choose in a similar fashion – and then rejoice when the Divine Justice condemns those souls who die without repenting. But we are not like the devils; as long as we are alive, we always retain the ability to choose. We can choose either good or evil and the Lord will respect our free will.
Similarly, we can choose to trust in Him or not. The words above describe His response if our choice is one of distrust, while the majority of St Faustina’s Diary talks of His response when we choose to trust in Him, and the graces flowing from that trust speak for themselves.
Trust is the key.