By nature, an adult unbeliever is under the control of the ruler of this world. God has nothing to do with unbelievers other than to take out from Jews and Gentiles a people for His name. “As it is written: ‘After this I will return and will rebuild the tabernacle of David, which has fallen down; I will rebuild its ruins, and I will set it up; so that the rest of mankind may seek the LORD, even all the Gentiles who are called by My name, says the LORD who does all these things’” (Acts 15:15-27).
God is not interested in the marriage, divorce and remarriage of unbelievers. Churchgoers who claim to belong to Church denomination have no rightstanding with God. Christians are forbidden from being yoked in any manner with them.
Our duty is to lead them to Christ so that their sins can be forgiven and they receive the gift of eternal life. Marital union between a child of God and a child of the devil is an aberration but God has opened a window of mercy in expectation of regeneration.