The answer
In our Coptic Orthodox faith, marriage is a Mystery (Sacrament) and therefore it has to be officiated in the church. It is considered a union between three, man and woman and God. We believe that God unite the two to become one in Him "So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate" (Mt 19:6). The person who marries an unbeliever chooses with his/her own freewill to separate themselves from the Lord to join in an earthly union with a non believer. "Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness? And what accord has Christ with Belial? Or what part has a believer with an unbeliever?" (2 Cor 6:14-15).So the question should really be: would a Coptic bishop (or priest) officiate such a marriage between a believer and a non believer and the answer is clearly "no". In order for this couple to be married in the Coptic Orthodox Church, the person concerned has to first believe in our Lord Jesus Christ and be baptized.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)