Question: I have been reading St. Faustina’s diary and have been saying the novena of the Chaplet of Divine Mercy for some years now. When saying these prayers, I always wonder why we need to pray for meek and humble souls, the souls of little children, the souls who especially venerate and glorify God’s mercy, all devout and faithful souls, etc. Isn’t God naturally extra merciful to such souls, as well as the souls of priests and religious who have devoted their lives to him? For example, my parents lost their first two children: my brother at age three and, years later, my sister at age five. Is God not automatically merciful to them, who hadn’t even reached the age of reason? These groups comprise almost half of those we pray for.
— Mary Ellen Handelman, via email
Answer: The categories of human beings described in the novena and in your question are still living in this world as members of the Church Militant. Hence they are needful of prayer precisely because of their innocence and holiness. Satan and his fallen angels seek above all to attack and bring ruin upon those who serve God here and the demons often increase their attacks by the very fact that such holy souls are young, or meek or faithful.
This “makes sense” in terms of a strategy. The devil does not usually need to attack those who are wicked since they are already numbered in his ranks. Rather, he fixes his attacks on those who are not among his followers and are, by holy lives, assisting the kingdom of God. No warring and wicked king attacks his own allies; he attacks his enemies and those who are allied with God.
A special hatred from Satan
The Book of Revelation says of Satan, “Then the dragon became angry with the woman (Mary and allegorically the Church) and went off to wage war against the rest of her offspring, those who keep God’s commandments and bear witness to Jesus” (Rev 12:17). Jesus also speaks to the special hatred the world has toward those who are faithful: “If the world hates you, realize that it hated me first. If you belonged to the world, the world would love its own; but because you do not belong to the world, and I have chosen you out of the world, the world hates you” (Jn 15:18-19). Hence the faithful, the humble, the lowly, the devout and the little children are most deserving of our prayers and most needful of them given the special hate that Satan has for them.
As for your lost siblings described in your question, this is a different matter. They have died to this world and are no longer under the further power of Satan to afflict them. Since they died very young, presumably after baptism, it is likely they are in heaven and only improbably in purgatory. So, while the prayers for their happy repose may benefit them living, the novena prayers of Divine Mercy, placing them behind the veil of Jesus’ most Sacred Heart and which are appropriate for the Church militant, are not necessary for them. They are already in his care in the heavenly realms.