The answer
The Antiochian Orthodox Church is a Chalcedonian Church and is part of the Eastern Orthodox group of Churches while the Coptic Orthodox Church is a Non-Chalcedonian Church and part of the Oriental Orthodox group. These two groups are not in full communion with each other. Therefore Coptic Christians cannot partake of the Communion at the Antiochian Church.Answered by His Eminence Metropolitan Youssef (opens in a new tab)