On the contrary, Dionysius says (Ep. ad Demophil.): "It seems presumptuous for such a man, one to wit who is not enlightened, to lay hands on priestly things; he is not afraid nor ashamed, all unworthy that he is to take part in Divine things, with the thought that God does not see what he sees in himself; he thinks, by false pretense, to cheat Him Whom he falsely calls his Father; he dares to utter in the person of Christ, words polluted by his infamy, I will not call them prayers, over the Divine symbols." Therefore a priest is a blasphemer and a cheat if he exercises his order unworthily, and thus he sins mortally: and in like manner any other person in orders.
Further, holiness of life is required in one who receives an order, that he may be qualified to exercise it. Now a man sins mortally if he present himself for orders in mortal sin. Much more therefore does he sin mortally whenever he exercises his order.