What is sexual immorality?

In God's sight immoral behaviour is so abominable that Paul had to write to Ephesus: "But fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints" (Eph. 5: 3). This means that we should not mention these things frivolously and so make little of them. The Bible speaks very clearly as to God's judgment about these sins. Holy Scripture not only calls prostitution fornication, but all extramarital intercourse, even where there may be the intention to get married, and even if it is done only once (cf. Gen. 34 and 38). In the world today the word fornication is only used in connection with the first meaning. In the New Testament, however, extramarital intercourse in general is called fornication, that of married persons is called adultery, and both are condemned as abominable sin (Matt. 15: 19; 1 Cor. 6: 9; Heb. 13: 4).

In God's sight immoral behaviour is so abominable that Paul had to write to Ephesus: “But fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints” (Eph. 5:3). This means that we should not mention these things frivolously and so make little of them. The Bible speaks very clearly as to God's judgment about these sins. Holy Scripture not only calls prostitution fornication, but all extramarital intercourse, even where there may be the intention to get married, and even if it is done only once (cf. Gen. 34 and 38). In the world today the word fornication is only used in connection with the first meaning. In the New Testament, however, extramarital intercourse in general is called fornication, that of married persons is called adultery, and both are condemned as abominable sin (Matt. 15:19; 1 Cor. 6:9; Heb. 13:4).

The whole of Scripture is full of the errors of fornication (Acts 15 v 29) and adultery (Exodus 20 v 14). The first is sexual relationship outside of marriage and the second sexual relationship with a married person. We must clearly state that physical affection is only intended by God for one man and one woman and that within the confines of marriage and to a very limited extent by a couple committed to marriage (see previous chapter).

According to Scripture, the sin of fornication not only refers to prostitution, but to any pre- or extramarital intercourse. We saw this earlier when we considered verses 27-30. Fornication is also adultery when at least one of the persons involved is married. Here the general term, "fornication," is used, although the verse deals especially with adultery. It seems rather far-fetched to interpret "fornication" here as implying immoral behaviour before the marriage, of which the husband learns only after the wedding.

The subject of moral defilement is taken up in 1 Cor. 5. A case of fornication had arisen in the Corinthian assembly. Fornication seems to be a term used in the Scriptures to encompass all kinds of sexual sins. In this case it was adultery-made worse as he was sinning against his own father-incest. Such a person must be excluded by the assembly from all fellowship. A list of similar serious sins is given in verse 11 and again in chapter 6 verses 9-10. These do not seem to be comprehensive, but in 2 Tim 3:2-4 we have another list of those persons from which a Christian must turn away, which seems to fill up any that are lacking.

"You shall not commit adultery" is the seventh commandment. Adultery is the corruption of the marriage bond, and the prohibition would certainly extend to every kind of such corruption whether persons are married or not. In the New Testament, though the words, "Ye shall not" are not used, yet the evil of fornication is no less warned against (Acts 15:29; 1 Thes.4:3-4). Homosexuality is worse still -- a most flagrant corruption of the bond of marriage (Rom.1:26-27).

This was very common among the Gentiles, which accounts for its being mentioned in the message sent from the conference at Jerusalem to the Gentiles, Acts 15:20, 29; and its being so often prohibited in the epistles. The word is sometimes used where 'adultery' is the sense. Matt. 5:32; Matt. 19:9. It often has in the O.T. a symbolical reference to the turning from God to idols. 2 Chr. 21:11, 13; Isa. 23:17; Ezek. 16:15, 26, 29; and in the N.T. to unfaithful intercourse with Babylon, the mother of harlots. Rev. 14:8; Rev. 17:2, 4; Rev. 18:3, 9.

Choosing to live together rather than marry is prevalent in the world around us. This is clearly fornication; there is no commitment to marry and no public declaration of marriage. The laws of most countries states that marriage must be lawfully enacted and Romans chapter 13 verse 1 tells us "the powers that be are ordained of God", they must, therefore, be obeyed.

As part of the blessing of marriage God has given us the pleasure of showing love through physical union and the freedom of the display of mutual affection; all within the bounds of a secure relationship.

In the marriage relationship there is complete freedom in this respect but outside marriage this is forbidden as we can clearly see from our scripture. The world does not see this distinction and the holiness and purity that God intended is destroyed. This relaxation of God's standard where physical relationships are entered into wherever and with whoever one chooses, can only bring guilt and misery.

The Lord Jesus now explains that before God it is not just the accomplished act that is sin, but the looking with lust on a woman, for this is adultery in the heart. The word “adultery” shows that either the man or both are married. Nevertheless, no unmarried believer should think that these words of the Lord have nothing to say to him.

The Lord is not speaking here about accidental, unintentional looks which can hardly be avoided, but about the conscious covetous looking: “Whosoever looketh on a woman to lust after her … ” The intentional look is therefore preceded by the sinful thought in the heart.