In Matthew 5:27-36 Jesus addresses the issues of lust and divorce,
“You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart. If your right eye causes you to sin, tear it out and throw it away. For it is better that you lose one of your members than that your whole body be thrown into hell. And if your right hand causes you to sin, cut it off and throw it away. For it is better that you lose one of your members than that your whole body go into hell. It was also said, ‘Whoever divorces his wife, let him give her a certificate of divorce.’ But I say to you that everyone who divorces his wife, except on the ground of sexual immorality, makes her commit adultery, and whoever marries a divorced woman commits adultery.
Again you have heard that it was said to those of old, ‘You shall not swear falsely, but shall perform to the Lord what you have sworn.’ But I say to you, Do not take an oath at all, either by heaven, for it is the throne of God, or by the earth, for it is his footstool, or by Jerusalem, for it is the city of the great King. And do not take an oath by your head, for you cannot make one hair white or black. Let what you say be simply ‘Yes’ or ‘No’; anything more than this comes from evil.”
In this section, Jesus handles lust/adultery, divorce and oaths. The seriousness of these sins is closely related to each other and to the idea of covenant relationships; in particular, marriage. Marriage is a lifelong covenant made before God between two people; it is a binding commitment of faithfulness to pursue oneness with each other. In the case of adultery, Jesus again makes it clear that the intention behind the action is just as sinful as the action itself. To lust after a person to whom you are not already married is to desire to become intimately one with someone different than the person to whom you have already pledged yourself. This is equivalent to the breaking of your established covenant of marriage. Jesus tells us it would be better to tear out (violently eradicate) than to live with whatever may cause us to violate the oaths of our covenant.
In the case of divorce, it is the same as lust; the illegitimate breaking of an established covenant. Marriage is a forever covenant that is only to be broken by death. To pursue divorce (apart from biblical grounds) is to pursue an illegitimate and, therefore, sinful breaking of a covenant. To break our covenant of marriage is to break our oath. It means that we have broken our word. Not only have we lied and are no longer trustworthy, we are also in breach of contract and subject to legal consequence.
However, no matter how much we may be tempted to (and in actuality) break our covenants with others, our perfect Father will never break his covenant with us. He will never leave us for another people. He will always keep his word. Through Christ, God the Father has established a new and everlasting covenant with his people. This covenant is “not like the covenant that God made with our fathers on the day when he took them by the hand to bring them out of the land of Egypt, his covenant that we broke, though he was our husband” (Jer 31:32). In this covenant, we, as God’s children, live in intimate oneness with God. Even though we may pursue other gods and consistently cheat on and be unfaithful to God, he will remain faithful to us. God will not abandon us. God will not divorce us to marry himself to another people. He made an eternal covenant with us and will be forever true to his word. As he says in Hosea 2:
“Therefore, behold, I will allure her . . . and speak tenderly to her. And in that day, declares the LORD, you will call me ‘My Husband’ . . . And I will betroth you to me forever. I will betroth you to me in righteousness and in justice, in steadfast love and in mercy. I will betroth you to me in faithfulness. And you shall know the LORD.”
God will remain faithful to his adopted covenant children who he purchased through the blood of Christ. There is nothing that we can do as his children to cause him to reject us.
“For the LORD your God is a merciful God. He will not leave you or destroy you or forget the covenant with your fathers that he swore to them” (Deuteronomy 4:31).