Anyone who believes that God is most merciful, has to accept Lord Krishna as the true God, because only He gave the most merciful teachings.

“My dear Lord, devotees who have fully dedicated their lives unto your lotus feet certainly observe your presence as Paramātmā in each and every being, and as such they do not differentiate between one living being and another. Such persons treat all living entities equally. They never become overwhelmed by anger like animals, who can see nothing without differentiation.” (Srimad-Bhagavatam 4.6.46)

“Devotional service executed by a person who is envious, proud, violent and angry, and who is a separatist, is considered to be in the mode of darkness. (Srimad-Bhagavatam 3.29.8)

“One who offers Me respect but is envious of the bodies of others and is therefore a separatist never attains peace of mind, because of his inimical behavior towards other living entities. (Srimad-Bhagavatam 3.29.23)

“A yogi should see the same soul in all manifestations, for all that exists is a manifestation of different energies of the Supreme. In this way the devotee should see all living entities without distinction. That is realization of the Supreme Soul. (Srimad-Bhagavatam 3.28.42)

“One who is not envious but is a kind friend to all living entities – Such a devotee of Mine is very dear to Me.” (Lord Krishna, Bhagavad-Gita 12.13-14)

“Who is friendly to every living entity, certainly comes to Me.” (Lord Krishna, Bhagavad-Gita 11.55)

“I am the benefactor and well-wisher of all living entities.” (Lord Krishna, Bhagavad-Gita 5.29)

“The living entities in this conditioned world are My eternal, fragmental parts.” (Lord Krishna, Bhagavad-Gita 15.7)

“All living beings are but part of the Supreme, or, in other words, that they are Mine.” (Lord Krishna, Bhagavad-Gita 4.35)

“One is my brother and the other is not – is the thinking of a narrow-minded person. For those who are broad-minded, liberals, or noble people, the entire world is a one big family.” (Maha Upanishad, Chapter 6, Verse 72)

“I envy no one, nor am I partial to anyone. I am equal to all.” (Lord Krishna, Bhagavad-Gita 9.29)

The Most Merciful Prayer is in the Vedic scripture

“Om May all be happy
May all be free from illness
May all see what is good
May no one suffer
Om peace, peace, peace”
(Brihadaaranyaka Upanishad 1.4.14)