Luke 16:15-18
15 And he said unto them, Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God.
16 The law and the prophets were until John: since that time the kingdom of God is preached, and every man presseth into it.
17 And it is easier for heaven and earth to pass, than one tittle of the law to fail.
18 Whosoever putteth away his wife, and marrieth another, committeth adultery: and whosoever marrieth her that is put away from her husband committeth adultery.
Divorce and remarriage is a common practice in modern times. Remarriage after divorce and marrying a divorcee are things highly esteemed among men. Unfortunately this is not a practice only among those that do not profess faith in Christ. There are just as many, if not more, people that profess to be born again that practice this sin. The purpose of this writing is to help the children of God deal with people who are living in this sin.
In the verses given above Jesus says that a person that divorces and remarries committeth adultery and if a person marries a divorcee they committeth adultery. "Committeth" is present-progressive tense, which means that it is a continuous action. That is to say, the act of remarriage after divorce or marrying a divorcee puts one in a continual state of adultery, and as such they have no part in the kingdom of God (1 Corinthians 6:9-10). The only way to be free from such adultery is to confess and forsake that sin (Proverbs 28:13). Mere confession of sin has never been enough to get forgiveness, God has always required for people confessing sins to forsake the sins.
With all of this in mind, how do you, as a child of God deal with people that are in this sin of adultery? You need to be mindful to be loving but honest toward them.
1 Thessalonians 4:12
12 That ye may walk honestly toward them that are without, and that ye may have lack of nothing.
Colossians 4:5
5 Walk in wisdom toward them that are without, redeeming the time.
Only God knows the person and He can give you wisdom on how to deal with them. It may be harder if you are talking with someone that claims to be a Christian because so many of them have been given excuses for their pet sin. A new convert may more readily accept the truth because they have not spent years covering up for and excusing their sins. It may be hard, but you need to recognize some people will not leave the lusts of the flesh for Christ. They may want religion, but they do not want to deny self and take up their cross while following Christ.
2 John 1:9-11
9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
10 If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed:
11 For he that biddeth him God speed is partaker of his evil deeds.
Whatever you do you need to be very careful about any interactions and time spent with such people. God does want you to walk in love toward all the unsaved and the saved, but you need to be careful how close you get with people that profess Christ but deny Him in their actions.
Rules for dealing with people in such sin: