Exodus 20:14

Marriage was God's gift to His creatures. He set it up before the Fall — before sin entered the world. He kept it going after the Fall. He held it as something no one may break, even before the law was given (Gen. 12:17; 20:3). He then guarded it by clear commands in the law (Ex. 20:14, 17). The Lord confirmed that it is holy (Matt. 19:3-9), and the New Testament says it is honourable for everyone (Heb. 13:4). Adam must have felt how much temporal enjoyment he had lost through the Fall. But God kept this blessing for him and for his children after him. It was His original gift for the happiness and welfare of people on earth.

"You shall not commit adultery" is the seventh commandment. Adultery corrupts the marriage bond. The command reaches every corruption of that bond, whether the people are married or not. The New Testament does not use the words "You shall not," but it warns against sexual sin just as strongly (Acts 15:29; 1 Thess. 4:3-4). Homosexuality is worse still — a most flagrant corruption of the bond of marriage (Rom. 1:26-27).

In the Old Testament, adultery means being unfaithful to your husband or wife to satisfy lust. God dealt with it very severely. According to the law of Sinai this sin had to be punished with death (Lev. 20:10; Deut. 22:22-24). The law was first of all God's set of rules for the outward, public life of His people on earth. So it punished only the finished act, even though the tenth commandment also forbade wanting your neighbour's wife... However, the mere outward keeping of this and all the other commandments could not justify him before God.

Here the Lord points to the human heart and shows that adultery has its source there. This is not a "spiritualising of the law," as is sometimes said. He says for the first time what every honest Israelite had to learn by experience. Anyone who tried to keep the command "You shall not commit adultery" found inside himself the very lusts that lead to the acts God forbids. And he had no strength to beat them. The lusts were even stirred up by the commandment: "I would not have known what it is to covet if the law had not said, 'You shall not covet'" (Rom. 7:7-11).

Anything in our life, our habits, or our service that puts a soul in danger of giving in to these feelings must go. We should never spare it. We should leave it, whatever it costs. There must be the cutting off of everything hurtful to the soul... Cutting off a hand or an eye pictures a heart that judges itself honestly. It does not excuse itself by saying the sin was never carried out. It gives up whatever led towards the sin.

In the acts listed here, people show how constantly they break the second half of the law — the commands about how we treat other people (Matt. 22:39; Mark 12:31). Love is the fulfilling of the law; it thinks no evil, and does no harm. So loving your neighbour keeps you from breaking each of these commands against harming him. Paul sums up all these commands in one. He writes to the church at Rome: "For the commandments, 'You shall not commit adultery, You shall not murder, You shall not steal, You shall not covet,' and any other commandment, are summed up in this word: 'You shall love your neighbour as yourself'" (Rom. 13:9).

Adultery, or idolatry — "with their idols they have committed adultery" (Ezek. 23:37) — is the sin God charged Israel with long ago, because she was His wife (Jer. 3:14; Isa. 54:1). For this He divorced her. But in His purpose and grace, the LORD will bring Israel back into that blessed relationship. She will never lose it again.

This is not just a statement giving marriage dignity. It is a command. It calls us to live out the relationship well and to keep it free from every trace of impurity. We are told to honour it, not in one way or another, but "in all things." So it is not a badge of respectability that people get simply by being married. It is a serious charge to married believers: use the relationship in a way that pleases the Lord in every detail.

"Flee from sexual immorality." Here we are not told to fight, but to keep far away, as Joseph ran from Potiphar's wife. Other sins may not involve the body in this way, but this is sin against one's own body. And besides our bodies being members of Christ, we are now told, "your body is a temple of the Holy Spirit within you."