For the feast of St. Thomas Aquinas, January 28 ~ On Charity and Mortal Sin

"It must be said that charity can, in no way, exist along with mortal sin."
~St. Thomas Aquinas, Quaestiones disputatae: De caritate.

The image is "The Temptation of St. Thomas Aquinas" by Diego Velazquez (1632)

Here is the quote in more context:

Article 6: Whether There Can Be Charity With Mortal Sin?

I answer. It must be said that charity can, in no way, exist along with mortal sin. To prove this, it must be considered, first, that every mortal sin is directly opposed to charity. Whoever chooses something in preference to something else, loves better that which he first chooses. Whence, because man loves his own life and his own continuance more than pleasure, however great that pleasure may be, he is drawn away from pleasure if he thinks that it is infallibly destructive of his own life. This is explained by Augustine when he writes in the LXXXIII Quaestionum, that there is no one who fears pain more than he who seeks pleasure. Sometimes we even see that the most savage of beasts will avoid the greatest pleasures because of the fear of pain. However, one sins mortally in this, that he prefers something other than to live according to God and to cling to God. Thus it is clear that whoever sins mortally, by this fact he loves some other good more than he loves God; for if he would love God, he would choose to live according to God more than to obtain some temporal good. However, it is of the very essence of charity that God be loved above all things, as is clear from what is said above. Therefore every mortal sin is contrary to charity.

The full treatise is well worth reading and may be found here: https://isidore.co/aquinas/english/QDdeVirtutibus2.htm#6