2Corinthians 5:17-21 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new. And all things are of God, who has reconciled us to himself by Jesus Christ, and has given to us the ministry of reconciliation; To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and has committed unto us the word of reconciliation. Now then we are ambassadors for Christ, as though God did beseech you by us: we pray you in Christ’s stead, be you reconciled to God. For he has made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
From 1Thessalonians 4:3-18 we see fourteen requirements of the will of God and of sanctification:  Abstain from fornication or all kinds of sexual sins (4:3; Matt. 5:32).  Know how to possess the vessel in sanctification and honour (4:4).  Not in the lust of concupiscence or strong sexual desire (Col. 3:5). Here it means excessive sexual lust like that of the Gentiles who knew no bounds.  That no man defraud his brother by seducing his wife to corrupt her and break up a home (4:6). This still refers to sexual sins and not to cheating, for it is dealing with sexual uncleanness down to 1Thessalonians 4:7. Every type of perversion was practised among the heathen nations (other than Israel). Their gods, their rulers, and their teachers were examples of impurity. They had no system of ethics that forbade these practices. The Christian religion forbade them as worthy of death and hell and this has preserved the world from complete ruin to this day.  Walk in holiness, not in the uncleanness of sexual perversion (4:7; Rom. 1:24).  Do not despise men (4:8).  Love one another (4:9; 1Cor. 13:1-13).  Increase in love (4:10; 3:12).  Study to be quiet (4:11; 2Tim. 2:15).  Be diligent in business (4:11).  Work with your hands (4:11; 1Cor. 4:12; Eph. 4:28; 2Thess. 3:10).  Walk honestly before men (4:12).  Have a bright hope (4:13-17).  Comfort one another (4:18).
‘To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and has committed unto us the word of reconciliation.’ I.e., that is to say: God was in Christ, reconciling people to Himself. God does not impute sin to those who have confessed and are reconciled to Him (Rom. 4:7-8). God has committed to the reconciled the word of reconciliation. God has made the reconciled ambassadors for Christ to reconcile others (5:20; Rom. 5:10). God made Christ a sin-offering, that man might become righteous (5:21). ‘Sin for us’ – as a sin-offering; a sacrifice for sin (Matt. 26:28; Eph. 5:2; 1Pet. 2:24).