Whether ingratitude is always a mortal sin?

❌ Objection 1 : It seems that ingratitude is always a mortal sin. For one ought to be grateful to God above all. But one is not ungrateful to God by committing a venial sin: else every man would be guilty of ingratitude. Therefore no ingratitude is a venial sin.

❌ Objection 2 : Further, a sin is mortal through being contrary to charity, as stated above (Question [24], Article [12]). But ingratitude is contrary to charity, since the debt of gratitude proceeds from that virtue, as stated above (Question [106], Article [1], ad 3; Article [6], ad 2). Therefore ingratitude is always a mortal sin.

❌ Objection 3 : Further, Seneca says (De Benef. ii): "Between the giver and the receiver of a favor there is this law, that the former should forthwith forget having given, and the latter should never forget having received." Now, seemingly, the reason why the giver should forget is that he may be unaware of the sin of the recipient, should the latter prove ungrateful; and there would be no necessity for that if ingratitude were a slight sin. Therefore ingratitude is always a mortal sin.

❌ Objection 4 : On the contrary, No one should be put in the way of committing a mortal sin. Yet, according to Seneca (De Benef. ii), "sometimes it is necessary to deceive the person who receives assistance, in order that he may receive without knowing from whom he has received." But this would seem to put the recipient in the way of ingratitude. Therefore ingratitude is not always a mortal sin.