Deep apologies for asking this again,
When would sloth become a mortal sin? In St. Thomas Aquinas’s Summa Theologica, he says it becomes mortal when we have sorrow to do something for God, aka sorrow for the Divine good. Does this mean laziness in striving after virtues? Or the scorning at having to say a prayer even though one isn’t obliged to?
That’s not exactly what Thomas says. He does say this:
"Therefore sloth is a mortal sin in respect of its genus. But it must be observed with regard to all sins that are mortal in respect of their genus, that they are not mortal, save when they attain to their perfection. Because the consummation of sin is in the consent of reason: for we are speaking now of human sins consisting in human acts, the principle of which is the reason. Wherefore if the sin be a mere beginning of sin in the sensuality alone, without attaining to the consent of reason, it is a venial sin on account of the imperfection of the act. "
He’s referring to sloth as grave matter in the first sentence. He goes on to say, as with any other sin involving grave matters, it does not rise to mortal sin unless they, "attain to their perfection ". This is an action of reason not just a simple case of weakness of flesh.
“So too, the movement of sloth is sometimes in the sensuality alone, by reason of the opposition of the flesh to the spirit, and then it is a venial sin; whereas sometimes it reaches to the reason, which consents in the dislike, horror and detestation of the Divine good, on account of the flesh utterly prevailing over the spirit. On this case it is evident that sloth is a mortal sin.”
newadvent.org/summa/3035.htm
So, here ^ Thomas uses some pretty strong language to highlight when sloth becomes a mortal sin, as opposed to venial.
