Yet, the Bible also shows that a Christian who sins and does not repent should be expelled from the congregation in order to keep it spiritually pure. (1 Cor. 5:1-5, 11-13) That happened to a man in Corinth who openly lived an immoral life.

In the unusual case brought up in the question, scheming and deceit may well have been manifest. For example, a man (perhaps himself married) gets infatuated with someone else’s wife. There then may be hidden flirting, secret meetings and unrevealed displays of passion. Lies and deceit may be used to keep this from others, particularly the innocent mate or mates. In time the pair might run off together, and after unscriptural divorce may marry each other. They may well have calculated the outcome, realizing that disfellowshiping will follow. But they think that “maybe in a year or so” they can claim repentance and get reinstated, thus having things just the way they want. However, it is a grave mistake to presume on divine mercy. Galatians 6:7 guarantees: “God is not one to be mocked. For whatever a man is sowing, this he will also reap.” That Jehovah looks with disapproval upon fornication is seen in many scriptures and this should not be overlooked by those entertaining wrong desires.​—Compare Revelation 21:8; 22:15.