I have seen it suggested by a couple of sound Catholic sources recently that the promise of Divine Mercy Sunday is superior to that of a plenary indulgence, on the grounds that to gain a plenary indulgence fully one needs, in addition to the three conditions of sacramental communion, sacramental confession and prayer for the pope, also to be free from any attachment to or affection for sin. In contrast to this, it is said, our Lord promised to St Faustina that whoever received Holy Communion on this day would receive forgive of all their sins and of all punishment due to sin; without saying anything about the need to have no affection for sin.

Now, I certainly don’t want to weaken anyone’s devotion to the Divine Mercy. I’m fully convinced of the importance of the messages given to St Faustina, and I like to recite the chaplet (though I normally forget to begin the novena early enough, what with everything else). I also think the prayers of the chaplet are a providential remedy for the weakening of the sense of propitiation and the divine justice, which has been caused by the turning round of the altars and the excision from the Mass of Pope Paul VI of the most explicit sacrificial prayers.

Still, I question the idea that any non-sacrilegious communion on this day necessarily gains complete remission of temporal punishment. Christ’s words must be understood in the whole context of the Church’s life and faith, and if it were possible to gain complete remission of temporal punishment in this way, this would seem to make indulgences unnecessary. Everyone would acknowledge that when our Lord says ‘whoever receives Holy Communion on this day…’, He does not mean ‘even those who receive it in mortal sin and with no intention of repenting’. So I don’t think we can say that He must mean ‘even those who have an affection for sin’, simply because He doesn’t explicitly exclude these people from the promise.

Does that mean that the promise of the day is no different from that attached to any plenary indulgence? Not necessarily. In the first place, the promise appears to be, as it were, a plenary indulgence granted by Christ even independently of the keys of the Church. The formal indulgence was only decreed in the year 2002, 70 or so years after the revelation to St Faustina. One can certainly believe that the promise was valid before the indulgence was decreed; whether this would be a unique case in the history of private revelations, I don’t know.

Secondly, one can also believe that this promise is even more generous than other plenary indulgences; that the same degree of detachment from sin will win a greater remission of temporal punishment by a Holy Communion on this day, than it would if one were to perform another indulgenced work.  Only we need to be cautious about claiming more than this, I’d say.