What is sexual immorality?

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.

Fornication is nature without God. It is therefore sin, like every other act of God-forgetting wilfulness. But in a Christian it is doubly sin; for what he does, he does as a member of Christ's mystic body.

Instead of being regarded as a thing indifferent, or even as a trivial offence, this sin is to be dreaded and shunned as a leprosy; for it contaminates both soul and body. Other sins did so but in part; but this completely, by turning that which God has claimed for Himself to an use which He condemns. A wrong is thus inflicted on the body itself, by alienating it from its true honour as an instrument of righteous worship, and again degrading it to the service of sin. It is, therefore, morally, what idolatry is spiritually; and the dissuasive from both is expressed by the apostle in the same terms.

A Christian is expected to forget his first parentage in the remembrance of the second. He is not God's creature only, but His child... his mortal body is the temple of the Holy Ghost. Sent down by the Father in the name of Jesus, He occupies this earthly house as a pledge and witness of its coming change... Each Christian body is a temple of the Spirit, even as the collective assembly of saints is His temple... Thus a double duty is imposed on the Christian with respect to his own body. He is to manage and govern it with vigilance and godly decision, as a restive and unruly beast; he is to hold it in honour, and tremble to abuse it, because it is the temple of the living God.

But the doctrine that the body is for Christ decided another question, to which the depraved habits of the Corinthians gave rise. All fornication is forbidden. To us, with our present Christian habits of mind, it is a thing of course — to Pagans, new; but the doctrine exalts every subject. Our bodies are the members of Christ... he who is united to the Lord is one spirit. The Spirit whose fulness is in Christ is the same Spirit who dwells in me and unites me to Him. Our bodies are His temples. What a mighty truth when we think of it!

Moreover we are not our own, but were bought with a price — the blood of Christ offered for us. Therefore we ought to glorify God in our bodies, which are His — powerful and universal motive, governing the whole conduct without exception. Our true liberty is to belong to God. All that is for oneself is stolen from the rights of Him who has bought us for His own... We have here two mighty motives for holiness: the value of Christ's blood, at which we are purchased; also the fact that we are the temples of the Holy Ghost.

Throughout it is not mere acts the Lord demands, but state; the spiritual condition suitable for the kingdom of the heavens. As in the verses immediately preceding the Lord insists on a spirit of lowly grace, going immeasurably beyond Thou shalt not kill, so now on a purity as far beyond the non-commission of adultery.

The avoidance of the extreme act might satisfy a Pharisee or Scribe; but the Lord could not dispense with anything short of truth in the inward parts. To look at a woman lustfully was to commit adultery with her already in his heart; and it is not the outside only that God regards but the heart above all.

There is but one just cause for which it may be dissolved; or rather, marriage must be dissolved morally in order to terminate as a matter of fact. In case of fornication, the tie is all gone before God; and the putting away merely proclaims before man what has already taken place in God's sight.

The indulgence of lust is incompatible with entering the kingdom of the heavens. The law forbade the act of adultery; the Lord condemns even the looking licentiously as adultery committed already in the heart... God's mind is clear from the first; adultery alone justifies divorce.

Idolatry and fornication were known as evil, even before the law was given, and so too was the eating of blood, as Genesis 9:4 shows. God knows from the outset all that He will develop as time goes on.

He shows that whatever the special favour shown by God, men will get away from and deny it; and further, that instead of using grace to walk morally, they will take advantage of grace to allow of a kind of immorality — they will turn the grace of God into licentiousness.