What would turn resistance into schism?

The wall has a shape, and losing the shape loses the canon's protection. The markers are visible in history. Resistance becomes schism when it erects a parallel hierarchy and synod, a rival altar, in the ancient phrase; when it declares the Mysteries of the canonical Church void and rebaptizes her faithful; when the separation hardens from a temporary defence into a permanent identity with its own succession and its own anathemas against the Church herself.

Set the two patterns side by side. St Euthymius withdrew and returned; the Athonites of 1970 ceased commemoration and resumed it; St Maximus died out of communion with the sees, and left no rival church behind him, so that the Sixth Council had a Church to vindicate him in. Against these stand the separations that consecrated rival bishops and pronounced the whole Church graceless: whatever their sincerity, they stepped outside the canon's acquittal and into the very rupture it condemns. The line of this library is defined by refusing that step: the wall, not the rival altar; the fast from communion, not the founding of a church.

• Rival altar, the ancient mark of schism: a parallel hierarchy and worship set against the Church's own.
• The wall's shape, temporary, defensive, within the Church, awaiting the synod, the four conditions of the canon's protection.

Canon 15's acquittal and its logic; St Basil on parasynagogue; the historical cases catalogued in this library, especially the modern ecumenical question.

The Old Calendar separations that consecrated their own synods and declared the canonical Churches graceless illustrate the crossing of the line; the confessors this course has followed illustrate staying within it.

“If walling off is right, then the fuller separation is righter.” The canon's protection is not a spectrum but a shape; to exceed it is not more zeal but a different act, the one the canon condemns.

• The modern ecumenical question, case study
• Heresies & confessions, where this library stands