What does “before synodal condemnation” mean?

The canon protects those who separate “before synodical judgment” (πρὸ συνοδικῆς διαγνώσεως). Before judgment of what? Notice what the canon has already said: the heresy in question is one “condemned by the holy Synods or Fathers.” The teaching, in other words, already stands judged. What has not yet happened is the trial of the man.

On the reading this library defends, that settles the phrase's meaning: the faithful need not wait for the bishop's deposition before withdrawing, because the only judgment still outstanding is the one that concerns his person and office, which belongs to a synod and may be years away. The permissive school reads the same phrase as a reason patience may counsel waiting. The difference between the two readings is the subject of Lesson 5 and the Canon 15 page.

• πρὸ συνοδικῆς διαγνώσεως, “before synodical judgment”, the pivotal phrase; on our reading, before the deposition of the man, not before a fresh verdict on the teaching.
• κατεγνωσμένη αἵρεσις, an already condemned heresy, the canon's precondition; no new council is needed to identify it.

Canon 15 (861); the conciliar acts showing heretical hierarchs tried and deposed as bishops (Lesson 7); the Trikamenas study on the phrase.

St Maximus refused the Monothelite communion decades before the Sixth Council sat. He was not waiting for a synod to tell him Monothelitism was false, the faith already condemned it, but the deposition of the patriarchs who taught it had to wait for 680 to 681.

“Nothing may be done until a council speaks.” If that were the canon's meaning, its exception clause would protect no one, everyone acting before the synod would be condemned, which is the opposite of what it says. The canon exists precisely to shelter lawful action taken before the trial of the man.

• Canon 15, the two interpretations
• Lesson 7: does a heretical bishop automatically lose priesthood?