The Sixth Commandment
ONE of the closest of all bonds is that between husband and wife, and nothing can be more pleasing to both than to know that each is loved by the other with a true and tender love. On the other hand, nothing can be more painful than to feel that the lawful love one owes the other has been transferred elsewhere. Rightly, then, and in its natural order, is the Commandment which protects human life against murder followed by that which forbids adultery, and which aims at preventing anyone from daring to violate or destroy the holy and honorable bond of marriage, that [abundant] source of affection and love.
Twofold, then, is the obligation imposed by the Sixth Commandment - the one expressly forbidding adultery, the other implicitly commanding us to cultivate purity of mind and body.
Besides adultery, other sins against chastity are found punished in the writings of Moses. Thus the celebrated law proclaiming that there should be no harlot among the daughters of Israel [See, Deut. 23:18 Jer.Bible; Deut.23:17-18 NRSV, or the NIV.]; there is also the exhortation addressed by Tobias to his son: "My son, take heed to keep thyself from all fornication "[Tobit 4:12 in NRSV], while Ecclesiasticus says: "Be ashamed of looking upon a harlot."[ In the Jerusalem bible this verse is at Ecclesiasticus 41:22. And see the Douay-Rheims version of Sirac 41:22.] ["'Fornication' is sexual intercourse between partners who are not married to each other."*** From dictionary.com.]
In the Gospel also our Lord Jesus Christ tells us that: "Out of the heart proceed adulteries and fornications which defile a man"[Matt. 15:19]. While the Apostle, St. Paul, frequently and in the severest terms gives expression to his detestation of this vice; thus : "This is the will of God, your sanctification; that you abstain from fornication" [1Thess. 4:3] ; and: "[Flee] fornication"[1Cor. 6:18] and: "Keep not company with fornicators"[1Cor 5:9] ; again: "But fornication and all uncleanness, let it not so much as be named among you"[Eph. 5:3], finally: "Neither fornicators nor adulterers, nor the effeminate*, nor Sodomites**, shall possess the kingdom of God."[1Cor.6:9]
But the principal reason why adultery is expressly forbidden is this, that besides the turpitude which it has in common with other kinds of incontinence, it also involves a sin of injustice not only against one's neighbor but also against society at large. [Consider the problems for children when parents separate over infidelity and society's problems trying to help single family parents.]
Remember that every unchaste thought is forbidden by this commandment. This is evident in the words of our Lord: "You have heard it said thou shalt not commit adultery; but I say unto you that whosoever looketh at a woman to lust after her, hath already committed adultery with her in his heart." [Matt. 5:27-28.] [A thought that comes unbidden and unwanted is not the type of thought meant here. If a thought does come, it becomes sinful if you agree with it and/or entertain it.]
[The author suggests that we should avoid anything involving immodesty because it can easily encourage someone into sin.]
From Msgr. John Hagan, A Compendium of Catechetical Instruction, Vol. III, Browne and Nolan, Dublin. Imprimatur +Eduardus, Archbishop of Dublin (1928), pp. 302-08. This text is used for religious and educational purposes only.
*"effeminate" is sometimes translated "male prostitute". For example, the NRSV translates 1Cor. 6:9 as: "Do you not know that wrongdoers will not inherit the kingdom of God? Do not be deceived! Fornicators, idolaters, adulterers, male prostitutes, sodomites..." (For an objective discussion of the translation of the underlying Greek words by a gay evangelical christian see the Homosexuality and Christianity website and his position which was recommended on the Moral Theology page of the Internet Theological Resources associated with St. John's School of Theology in Collegeville, Minn. However these pages seem to have disappeared.) 1Cor. 6:9 is referred to in the Catechism of the Catholic Church sec. 2357.