By means of his free will man can give God loyal and affectionate service; but by means of the same free will he can also offend God by committing actual sin. This sin can be committed in many ways. It can be entirely within man's mind and heart, as when he deliberately takes pleasure in something evil pictured in his imagination (sin of thought) or when he deliberately wishes something evil, even though he knows he can never do it (sin of desire). Or, a person can make use of his bodily faculties to offend Godby using his power of speech in bad language, such as blasphemy or cursing (sin of word), or by employing another bodily power, such as his hands to murder or to steal (sin of action). Finally a person can commit sin by neglecting to do something which he is obliged to do, as when he fails to go to Mass on Sunday or to help others in their need when he could and should do so (sin of omission).
When a person is in doubt as to whether or not a certain action is sinful, he is not allowed to do it until he has made reasonable efforts to solve his doubt. Usually the most practical way to solve such a doubt of conscience is to ask a priest, particularly in confession.
The most important division of actual sins, mortal and venial, is explained at length in the catechism. Some persons have the idea that it is sufficient to avoid mortal sins; they freely commit venial sins. This is a false notion. Venial sin is a great evilnext to mortal sin, it is the greatest evil in the world, worse than the most painful sickness or the most dreadful form of death. One who pays no heed to venial sins will soon fall into mortal sin. It is true, on account of the weakness of human nature brought on by original sin no one (unless he receives a special privilege from God, such as was given to the Blessed Virgin Mary), can abstain for a long time from semideliberate venial sins, committed without full consent of the will. But all should strive to avoid every deliberate sin, whether it be venial or mortal. No one can ever claim that God does not give him sufficient grace to avoid such sins, for St. Paul tells us: "God is faithful and will not permit you to be tempted beyond your strength" (1 Cor. 10:13).
However, venial sins, even though frequently committed, do not unite to form a mortal sin, though sometimes the matter involved in several sins, each of which in itself is venial, will accumulate to form a large amount, and thus eventually a mortal sin will be committed. Thus, if a clerk would steal fifty cents a day from the store in which he is employed, the total amount would soon become sufficient to render him guilty of mortal sin, even though the amount of each theft taken in itself would constitute only a venial sin.
We must all be on our guard against the capital sins, which are the sources of all the other sins. It is not sufficient to resolve not to give in to the capital sinswe must strive to practice the opposite virtues. Every one should honestly examine his own character and find out his predominant passionthat is, the type of sin to which he is most inclinedand try earnestly to overcome it. With God's grace, he shall eventually succeed.
We must particularly avoid the near occasions of sin. Nowadays there are many occasions of sin in the world, such as bad books, heretical or improper radio programs, indecent motion pictures, vile theatrical exhibitions, and persons who try to lead others into sin by their bad speech or wicked conduct. Those who frequent unnecessarily the occasions of sin are running a great risk "He that loveth danger shall perish in it" (Ecclus. 3:27).
Above all, we have prayer and the sacraments to strengthen us against temptation to sin. Whenever an inclination to offend God besets our soul, our first thought should be to have recourse to prayer. It need not be a long prayer; even the devout calling on the names of Jesus and Mary will be of great help. And one who frequently receives Our Lord in Holy Communion obtains immeasurable spiritual strength against the weakness and evil inclinations of his nature that are the cause of so many sins.
RESOLUTION: Resolve frequently to suffer any evil, even death, rather than offend God by sin, especially mortal sin.