There are many people who become Christians after they were divorced. Obviously some have also been remarried before they became Christians as well.
God forgives all sins and this includes any involving divorce and remarriage. A person is a new creation when they become a Christian. Ezekiel 36:26 says, “I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh.”
As Christians we are called to repent of past sins and not repeat them. This doesn’t mean that a person who is remarried and is guilty of adultery because of it should leave their current spouse. But it does mean that a divorced person should remain single if they have not remarried.
Paul writes in 1 Corinthians 7:17-24:
17 Nevertheless, each one should retain the place in life that the Lord assigned to him and to which God has called him. This is the rule I lay down in all the churches. 18 Was a man already circumcised when he was called? He should not become uncircumcised. Was a man uncircumcised when he was called? He should not be circumcised. 19 Circumcision is nothing and uncircumcision is nothing. Keeping God’s commands is what counts. 20 Each one should remain in the situation which he was in when God called him. 21 Were you a slave when you were called? Don’t let it trouble you—although if you can gain your freedom, do so. 22 For he who was a slave when he was called by the Lord is the Lord’s freedman; similarly, he who was a free man when he was called is Christ’s slave. 23 You were bought at a price; do not become slaves of men. 24 Brothers, each man, as responsible to God, should remain in the situation God called him to.
There are numerous reasons for divorce. In the article “Should I Get Remarried?” the times when remarriage is appropriate is discussed. There are very few times that it is clear from scripture that remarriage is acceptable. This applies to a person who was divorced before they became a Christian as well.
Even though the sins of the past are forgiven and a Christian is a new creation, there are still consequences of past actions. This is no different from a prisoner who becomes a Christian. Their crimes have been forgiven but they must still serve the sentence they have been handed.
We cannot change the actions of our past. God has forgiven them and they are behind us. But they are still a part of our history for better or worse. We are responsible for our current actions however. No matter what we may have done in the past, it is the decisions that we make today that matter most now.
This is why Paul tells the Corinthians to remain in the current situation. All of 1 Corinthians 7 is about marriage which is why we know that Paul is addressing marriage in the passage above. It is because the past is past that we should remain in our current situation. We can’t change it no matter how much we may like to. We are responsible for our actions now which is why we must make the best choices we can and to live for Christ.
A person who was divorced before they became a Christian has consequences of their past actions just as everyone who becomes a Christian must deal with consequences of their past actions. A Christian must strive to not repeat sins of the past and instead strive to live their life according to the Word of God.