It may be necessary before we proceed to explain the word anathema; it means condemnation and excommunication until restored after sincere repentance. In some cases it may not be only a temporal ban, but a curse. Indeed, there are some members of the Church today, Christians, who do not fully realize that the Church of Christ is a living organism, which, through the supernatural indwelling of the Holy Spirit, exists as a moral being, empowered within her sphere not only to bless, but also to curse. Such ones of course do not read the Bible. Those who studied the Epistles of the Apostles know that it was required of the Corinthians to put away from among themselves that wicked person (1 Cor. v: 13). Likewise the command was given to Titus, hear: A man that is an heretic after the first and second admonition reject (Tit. iii: 10). Did not our Lord Jesus Christ say: If thy brother neglect to hear the Church, let him be to thee as an heathen man and a publican? (Matt. xviii: 17.) And again our Lord speaks: Whatsoever ye shall bind on earth shall be bound in heaven; and whatsoever ye shall loose on earth shall be loosed in heaven (Matt. xviii: 18).
To them who do not accept with a pure and simple faith and with all their soul and heart the extraordinary miracles of our Saviour and God and of the Holy Theotokos who without stain gave birth to Him, and of the other saints, but who attempt by sophistic demonstration and words to traduce them as being impossible, or to misinterpret them according to their own way of thinking, and to present them according to their own opinion,
“They (viz. the Latinizers) have dishonored and corrupted the
Church by making her mingle with those putrid members that have
been cut off from her for many years and are subject to countless
anathemas, and through communion with them they have besmirched the spotless Bride of Christ.”
+ St. Mark of Ephesus, Epistle to Hieromonk Theophanes
Even if the whole universe holds communion with the [Latinizing] Patriarch, I will not communicate with him. For I know from the writings of the holy Apostle Paul: the Holy Spirit declares that even the angels would be anathema if they should begin to preach another Gospel, introducing some new teaching.