The answer
In partaking of the Holy Communion at the Catholic Church or any other church, we declare that we do agree and adopt all the dogmas and the beliefs of this church. As Coptic Orthodox, we do not agree with many of the dogmas of the Roman Catholic Church such as the Filioque, the Immaculate Conception, the Infallibility of the Pope, the Purgatory and many others things. This is why we cannot say that we have the exact faith and therefore cannot partake of the Eucharist at that church.To read more about the differences between the Orthodox and the Catholic Church check this website www.geocities.com/mgocsmbvli/orth_cath.htm.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)