Gambling is always a mortal sin? Really?
Gambling is a mortal sin, but not necessarily mortal for the person who is in ignorance in regards on this subject (so long as his gambling was moderate, that is. Excess in gambling always constitute mortal sin).
Council of Elvira (306), Canon 79: "
Christians who play dice for money are to be excluded from receiving communion [excommunication]. If they amend their ways and cease, they may receive communion after one year."
St. Thomas Aquinas: "We read in the Canons of the apostles (Can. xli, xlii): 'A bishop, priest or deacon who is given to drunkenness or
gambling, or incites others thereto, must either cease or be deposed; a subdeacon, reader or precentor
who does these things must either give them up or be excommunicated; the same applies to the laity.'
Now such punishments are not inflicted save for mortal sins. Therefore drunkenness [and gambling] is a mortal sin." (Summa Theologica, II:II, Q, 150, A, 2. Whether drunkenness is a mortal sin?)
MORE ON GAMBLING
St. Francis de Sales
CHAPTER XXXII. Of Forbidden Amusements.
DICE, cards, and the like games of hazard, are not merely dangerous amusements, like dancing, but they are plainly bad and harmful, and therefore they are forbidden by the civil as by the ecclesiastical law. What harm is there in them? you ask. Such games are unreasonable:—the winner often has neither skill nor industry to boast of, which is contrary to reason. You reply that this is understood by those who play. But though that may prove that you are not wronging anybody, it does not prove that the game is in accordance with reason, as victory ought to be the reward of skill or labour, which it cannot be in mere games of chance. Moreover, though such games may be called a recreation, and are intended as such, they are practically an intense occupation. Is it not an occupation, when a man’s mind is kept on the stretch of close attention, and disturbed by endless anxieties, fears and agitations? Who exercises a more dismal, painful attention than the gambler? No one must speak or laugh,—if you do but cough you will annoy him and his companions. The only pleasure in gambling is to win, and this cannot be a satisfactory pleasure, since it can only be enjoyed at the expense of your antagonist. Once, when he was very ill, S. Louis heard that his brother the Comte d’Anjou and Messire Gautier de Nemours were gambling, and in spite of his weakness the King tottered into the room where they were, and threw dice and money and everything out of the window, in great indignation. And the pure and pious Sara, in her appeal to God, declared that she had never had dealings with gamblers.
"I beg, O Lord, that thou loose me from the bond of this reproach, or else take me away from the earth. Thou knowest, O Lord, that I never coveted a husband, and have kept my soul clean from all lust. [17] Never have I joined myself with them that play: neither have I made myself partaker with them that walk in lightness." (Book of Tobias, 3:15-17) So, now when you KNOW gambling is disapproved by the Church and Catholic civil law, you have no excuse for doing so. Before you could be excused from mortal sin in regards to (moderate) gambling, but not now when you have been presented with Church teaching.