Of course all depends on what is the object of our imprecations.  One species of this vice contains blasphemy pure and simple, that is, a curse which attains something that refers to God in an especial manner, and as such is cursed.  The idea of God cannot be separated from that of the soul, of faith, of the Church, etc.  Malediction addressed to them reaches God, and contains all the malice of blasphemy.

When the malediction falls on creatures, without any reference to their relationship to God, we have cursing in its proper form with a special malice of its own.  Directly, charity alone is violated, but charity has obligations which are binding under pain of mortal sin.  No man can sin against himself or against his neighbor without offending God.

A curse may be, and frequently is, emphasized with a vow or an oath.  One may solemnly promise God in certain contingencies that he will damn another to hell; or he may call upon God to witness his execrations.  The malice of two specific sins is here accumulated, the offense is double in this one abominable utterance; nothing can be conceived more horrible, unless it be the indifferent frequency with which it is perpetrated.

The guilt incurred by those who thus curse and damn, leaving aside the scandal which is thereby nearly always given, is naturally measured by the degree of advertence possessed by such persons.  Supposing full deliberation, to curse a fellow-man or self, if the evil invoked be of a serious nature, is a mortal sin.

Passion or habit may excuse, if the movement is what is called “a first movement,” that is, a mechanical utterance without reflection or volition; also, if the habit has been retracted and is in process of reform.  If neither damnation nor death nor infamy nor any major evil is invoked, the sin may be less grievous, but sin it always is.  If the object anathematized is an animal, a thing, a vice, etc., there may be a slight sin or no sin at all.  Some things deserved to be cursed.  In damning others, there may be disorder enough to constitute a venial sin, without any greater malice.

Considering the case of a man who, far removed from human hearing, should discover too late, his forgetfulness to leave the way clear between a block and a fast-descending and ponderous ax, and, in a fit of acute discomfort and uncontrollable feeling consequential to such forgetfulness, should consign block, ax, and various objects in the immediate vicinity to the nethermost depths of Stygian darkness:  in such a case, we do not think there would be sin.

On the other hand, they in whose favor such attenuating circumstances do not militate, do the office of the demons.  These latter can do nothing but curse and heap maledictions upon all who do not share their lot.  To damn is the office of the damned.  It is therefore fitting that those who cease not to damn while on earth be condemned to damn eternally and be damned in the next life.  And if it is true that “the mouth speaks out of the abundance of the heart,” to what but to hell can be compared the inner soul of him whose delight consists in vomiting forth curses and imprecations upon his fellow-men?