The problem that those who believe the gospel and are baptised into Jesus Christ face here, is that marriage to a divorcee whose ex-spouse is still alive constitutes adultery.
Matthew 19:3 The Pharisees also came unto him, tempting him, and saying unto him, Is it lawful for a man to put away his wife for every cause? 4 And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female, 5 And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh? 6 Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder. 7 They say unto him, Why did Moses then command to give a writing of divorcement, and to put her away? 8 He saith unto them, Moses because of the hardness of your hearts suffered you to put away your wives: but from the beginning it was not so. 9 And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery.
The Law given through Moses permitted divorce for sexual unfaithfulness before marriage [i.e. fornication]. Sexual unfaithfulness after marriage [i.e. adultery] was a capital offence.
Leviticus 20:10 And the man that committeth adultery with another man’s wife, even he that committeth adultery with his neighbour’s wife, the adulterer and the adulteress shall surely be put to death.
To the woman taken in adultery Jesus said, “Go and sin no more”.
The only exception to this rule is if one partner in the marriage has committed adultery. Then, although forgiveness and reconciliation is recommended, divorce and subsequent remarriage is permissible. (see Matthew 5:32.
John 8:3 And the scribes and Pharisees brought unto him a woman taken in adultery; and when they had set her in the midst, 4 They say unto him, Master, this woman was taken in adultery, in the very act. 5 Now Moses in the law commanded us, that such should be stoned: but what sayest thou? 6 This they said, tempting him, that they might have to accuse him. But Jesus stooped down, and with his finger wrote on the ground, as though he heard them not. 7 So when they continued asking him, he lifted up himself, and said unto them, He that is without sin among you, let him first cast a stone at her. 8 And again he stooped down, and wrote on the ground. 9 And they which heard it, being convicted by their own conscience, went out one by one, beginning at the eldest, even unto the last: and Jesus was left alone, and the woman standing in the midst. 10 When Jesus had lifted up himself, and saw none but the woman, he said unto her, Woman, where are those thine accusers? hath no man condemned thee? 11 She said, No man, Lord. And Jesus said unto her, Neither do I condemn thee: go, and sin no more.
Marriage is intended to demonstrate the relationship between Jesusd Christ and the church – his bride.
2 Corinthians 11:2 For I am jealous over you with godly jealousy: for I have espoused you to one husband, that I may present you as a chaste virgin to Christ.
Concerning marriage, Paul writes to the Corinthians:
1 Corinthians 7:1 Now concerning the things whereof ye wrote unto me: It is good for a man not to touch a woman. 2 Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband. 3 Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband. 4 The wife hath not power of her own body, but the husband: and likewise also the husband hath not power of his own body, but the wife. 5 Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again, that Satan tempt you not for your incontinency. 6 But I speak this by permission, and not of commandment. 7 For I would that all men were even as I myself. But every man hath his proper gift of God, one after this manner, and another after that. 8 I say therefore to the unmarried and widows, It is good for them if they abide even as I. 9 But if they cannot contain, let them marry: for it is better to marry than to burn. 10 And unto the married I command, yet not I, but the Lord, Let not the wife depart from her husband: 11 But and if she depart, let her remain unmarried, or be reconciled to her husband: and let not the husband put away his wife. 12 But to the rest speak I, not the Lord: If any brother hath a wife that believeth not, and she be pleased to dwell with him, let him not put her away. 13 And the woman which hath an husband that believeth not, and if he be pleased to dwell with her, let her not leave him. 14 For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy. 15 But if the unbelieving depart, let him depart. A brother or a sister is not under bondage in such cases: but God hath called us to peace. 16 For what knowest thou, O wife, whether thou shalt save thy husband? or how knowest thou, O man, whether thou shalt save thy wife?
And to the Galatians:
Ephesians 5:22 Wives, submit yourselves unto your own husbands, as unto the Lord. 23 For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body. 24 Therefore as the church is subject unto Christ, so let the wives be to their own husbands in every thing. 25 Husbands, love your wives, even as Christ also loved the church, and gave himself for it; 26 That he might sanctify and cleanse it with the washing of water by the word, 27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish. 28 So ought men to love their wives as their own bodies. He that loveth his wife loveth himself. 29 For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church: 30 For we are members of his body, of his flesh, and of his bones. 31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh. 32 This is a great mystery: but I speak concerning Christ and the church. 33 Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband.
And to the Romans:
Romans 7:1 Know ye not, brethren, (for I speak to them that know the law,) how that the law hath dominion over a man as long as he liveth? 2 For the woman which hath an husband is bound by the law to her husband so long as he liveth; but if the husband be dead, she is loosed from the law of her husband. 3 So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man.
In the letter to the Hebrews we read:
Hebrews 13:4 Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge.
Jesus’ commandment is clear:
Matthew 19:9 And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery.
Fornication denotes sexual unfaithfulness during the betrothal period prior to marriage. This was the problem that Joseph thought he had:
Matthew 1:18 Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Spirit. 19 Then Joseph her husband, being a just man, and not willing to make her a publick example, was minded to put her away (i.e. divorce her) privily. 20 But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Spirit.
To divorce is contrary to the commandment of Christ. To marry a divorcee is contrary to the commandment of Christ. The only exception is as provided by the Lord himself in Matthew 5:32.
Separation is permitted:
1 Corinthians 7:10 And unto the married I command, yet not I, but the Lord, Let not the wife depart from her husband: 11 But and if she depart, let her remain unmarried, or be reconciled to her husband: and let not the husband put away his wife.
For those who find themselves mired in divorce, through no desire of their own, God is a merciful God, and Jesus Christ makes intercession for those who diligently seek him.
1 John 1:7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. 8 If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
I hope this helps.