In lieu of a simple reply to the above question, we could propose the following:

“Because it is forbidden by the 45^th and the 65^th Apostolic Canons, which respectively say that:  

«Any Bishop or Presbyter or Deacon who only prays together with heretics, should be excommunicated; and if they should permit them (the heretics) to perform anything as clergymen, they should be defrocked.»

and

«Should any clergyman or layman enter into a congregation of Jews or heretics to pray, he should be excommunicated and defrocked.»

However, we believe that this does not suffice as a reply, for someone who wants to know the REASON these canons were issued by the holy Apostles.

So it was that, in his desire to explain the reason for this prohibition, Saint Nicodemus provided us with certain comments on the subject, in the Pedalion.*

(Pedalion = Rudder: a collection of canons of the Orthodox Church, compiled by Saint Nicodemus of Mount Athos)

“Orthodox Christians must avoid heretics, and the rituals of heretics. Instead, they (the heretics) should be checked and counseled by the Bishops and the Presbyters, in the hope that they will come to understand, and thereafter turn away from their fallacy.  It is for this, that the present canon ordains that any Bishop or Presbyter who would accept as proper and true the baptism of heretics, or the sacrifice offered by them, such a person we command to be defrocked.  For, what agreement does Christ have with the devil?  Or, what share does a faithful person have, as compared to a faithless one?  Because, those who accept whatever is the heretics’, or have beliefs similar to them, or,  lesser still, do not have any willingness to free themselves of their cacodoxy, then, BY CONDESCENDING TO PARTICIPATE IN THEIR RITES, HOW WILL THEY (the clergy) BE ABLE TO CHECK THEM, SO THAT THEY MIGHT RESIGN FROM THEIR CACODOXY AND MISGUIDED HERESY? “ (Pedalion (Greek), pages 50-54)

Two, therefore, are the reasons according to Saint Nicodemus, that forbid Christians to pray together with heretics:

1. So that there shall be no communion of the faithful with the faithless, and Christ with the devil, and

2. So that in this way, clergymen will be able to check heretics, and "have the upper hand” when telling them that they are in a soul-condemning heresy, without the other person being able to retort: “Then why do you pray with us?”

Let’s examine these two reasons in more depth, beginning with the first one.

 

1. Why is common prayer considered a communing of the faithful with the faithless?  

Even though (as we have shown in a separate article) it is more than obvious to most people that other religions worship a god other than our own, this is not so obvious when it comes to heresies.  Could this also apply (that they believe in another God) to the Christian heresies?  

To begin with, the overwhelming majority of heresies contain THEOLOGICAL ERRORS. This means that the God they believe in is NOT the Christian God, but another, phony, counterfeit god; a nonexistent one.  And naturally, wherever the true God is absent, the void becomes occupied by the Devil!

Let’s take a look at some examples:

We shall begin with the anti-Triadic heretics, in which are included a large portion of Adventists, Russellites (Bible Studiers, Watchtower Witnesses, Evangelists, etc.), all of whom are Arianists, and a large portion of Pentecostals worldwide, who are Savellianists – in other words, those who believe that God is one person with three manifestations and not three individual Personae.  Most assuredly, there is a vast difference between a Pagan god (who is subject to the limitations of space and time), as is the “limited” god of the Jehovah’s Witnesses, or, a god who is solely a person, (and subsequently a servant of his own essence), as compared to our true, Triadic God.

But there are heresies such as the Monophysites who, while accepting the Triadic God, deny the two natures of Christ! Heretics such as these, however, believe in “another Christ” – a nonexistent one!  And those who do not have the Son, do not have the Father either! (John I, 2:23).

The same applies to the Papist believers, who, on account of the Filioque on one hand, and on the other hand on account of their Augustinian perception of God, whom they perceive as “essence” and not as Hypostasis, are essentially worshipping a false god, who is subservient to his essence and not vice-versa, which is the case with the true God.  And of course even the Papists are equally heretics, and sacrifice to demons, not to God.

Perhaps someone might insist, however