II Cor. 6:1-18
As he continued his letter, Paul warned the Corinthians about their associates. He reminded them of the importance of constantly being prepared for the judgment. Since tomorrow may be too late, the present is the time that one needs to be prepared.
Paul reinforced his credentials and authority as an apostle before giving the main body of his warning. He was very careful to live in a way that no one would speak evil of the gospel.
There were others, including Timothy who were working with Paul. He opened their lives as an informational letter to the Corinthians by listing their hardships and successes. They were able to see the true character of Paul and his associates and the love that he had for them. Any barrier between them and him would be placed by the Corinthians and not by him. He asked them as his children in the faith to return their affection to him.
God had commanded many times in the Old Testament that His people, the Jews keep themselves from associating with the heathen nations. He did not allow the marriage between Jews and heathens.
As Paul continued his warning, he said, “Do not be unequally yoked together with unbelievers.” He showed the contrasts between Christians and unbelievers. Business associations with people of the world have led many of God’s people into darkness and to the worship of idols (money, pleasure, etc.).
I have seen great heartache and suffering in marriages between believers and unbelievers. So many times, Christians give in to the unbelievers and lose their faith. Their children become confused and refuse to accept the gospel.
Paul said that God wants His people to come out from among those who are of this world. God wants them to be His sons and daughters and for Him to be a Father to them.