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Hello Father Angelo.

I wanted to ask you what are the sins against the ninth commandment?

And in what case are they mortal or venial?

My dear friend,

1. The Catechism of the Catholic Church on the Ninth Commandment says, “Don’t desire your neighbor’s house. Do not desire the wife of your neighbor, nor his slave, nor his ox, nor his donkey, nor anything that belongs to your neighbor (Ex 20:17). “But I say to you, everyone who looks at a woman with lust has already committed adultery with her in his heart (Mt 5:28)” (CCC 2513). 

2. And he continues, “Saint John distinguishes three types of inordinate desire or sexual desires: the lust of the flesh, the lust of the eyes, and the pride of life (1 Jn 2:16). According to the Catholic catechetical tradition, the ninth commandment forbids carnal sexual desires; the tenth is the desire of the goods of others “(CCC 2514).

3. Then specify what concupiscence consists of, “Concupiscence, in the etymological sense, can designate any vehement form of human desire. Christian theology has given this word the specific meaning of motion of the sensitive appetite that is opposed to the dictates of human reason. The Apostle Saint Paul identifies it with the opposition of the ‘flesh’ to the ‘spirit’” (Gal 5: 16-17). It is a consequence of the disobedience of the first sin (Gn 3,11). It generates disorder in the moral faculties of man and, without being a sin in itself, inclines man to commit sin (DS 1515).

4. Then, rather than presenting a list of sins that go against the ninth commandment, the Catechism of the Catholic Church speaks of the need to increase the purity of thoughts, eyes, and feelings. 

5. To get to the core of the matter, because your question requires precise answers that do not remain generic, I present to you the thought of St. Thomas. Commenting on this Commandment he writes,“Because of the corruption that followed (original) sin, no one escaped lust, except the Christ and the glorious Virgin.” Concupiscence sometimes appears together with venial sin, sometimes with mortal sin, when it takes over. The Apostle says, “Therefore, sin must not reign over your mortal bodies so  that you obey their desires” (Rom 6:12). He does not say, there is not, because, as he says elsewhere,        ‘For I know that good does not dwell in me, that is, in my flesh’ (Rom 7:18). (Explanation of the 10 commandments of the Law).

6. And here is how “Sin reigns in the flesh, first, when lust dominates in the heart, because of our consent.” Well, lust does not dominate when a thought passes in front of our mind or when it feels a disordered sensation, but when consent is given. And that is when one wants to do that particular thing “since before God will and doing are considered in the same way.”

7. Sin reigns in the flesh in a second way and that is when sexual desire dominates in the mouth, expressing the thought, “For the fullness of the heart the mouth speaks” (Mt 12:34). Again, “No foul language should come out of your mouth“ (Eph 4:29). Therefore St. Thomas says that it is not without fault who composes frivolous songs. So also thinks the philosopher Aristotle, for whom the poets who composed love verses had to be expelled from the cities.”

 8. Sin reigns in the flesh in a third way, when lust leads to action, and the members place themselves at the service of lust, “As you have offered your members to iniquity to serve in iniquity” (Rom 6:19 ). That is to say when thoughts and words lead to real disorder.

9. In concrete terms, it is difficult to establish when there is serious sin. St. Thomas himself says that in some cases there is only the venial, in others there is the grave because desire takes over. It can be said that there is serious sin in the first case, because there is already deliberation. In the others it will be necessary to evaluate the degree of the upper hand of the actions that arise.  

10. Finally, St. Thomas gives concrete indications to prevent sexual desires from reigning in our flesh. He writes, “To get out of this sin, it is necessary to work hard, because we have it inside, and the most difficult enemy to overcome is the one we have at home.” It can be won, however, in four ways: Avoiding external occasions: for example bad company and what can be an opportunity to fall into such sin: “Avert your eyes from a comely woman; gaze not upon the beauty of another’s wife. Through women’s beauty many perish, for lust to it burns like fire. “(Sir 9: 7) and ”Can a man take fire to his bosom, and his garments not be burned?”(Pr 6:27). That is why Lot was ordered to flee from all the surrounding area (Gn 19:27). Not giving space to thoughts: because they are the occasion that awakens lust. This is achieved by chastising the flesh, “I punish my body and reduce it to slavery” (1 Cor 9:27). By committing himself to prayer: “Unless the Lord guards the city, in vain does the guard keep watch” (Ps 127:1). Again, “I know that otherwise without God’s help I cannot contain myself” (Wis 8:21). Furthermore, “This kind does not come out except by prayer and fasting” (Mt 17:21). If there is a duel, and you want to help one and not the other, you have to support the first, take your support away from the other. There is also a continuous duel between Spirit and flesh. If you want the Spirit to win, you must give him support, and such is prayer. To the flesh, on the other hand, you have to deny support, and this is done by fasting, since fasting exhausts the flesh. Dedicating himself to lawful occupations: “Idleness is an apt teacher of mischief” (Sir 33:28). Sodom’s sin consisted of pride, bread to fill, abundance and idleness. Saint Jerome says, always do something good, so the devil will find you busy. Now, of all the occupations, the best is the study of the Bible. St. Jerome said “Love the study of the Scriptures and you will not love the vices of the flesh” (Letters II, 2). 

While I hope that you will always enjoy the “purity of heart that will make us see God and from now on allows us to see everything according to God” (CCC 2531), I will make you present to the Lord and I bless you.

 Father Angelo