Guibert blamed Eastern Christianity’s doctrinal instability for its fall into heresy.

Evidence

The faith of Easterners, which has never been stable, but has always been variable and unsteady, searching for novelty, always exceeding the bounds of true belief, finally deserted the authority of the early fathers. — John V. Tolan, Saracens, 783

Categorization

• XREF: Tenacity of the idea that a stable creed requires submission to founding authority — parallels the universalist vs. particularist tension in Communication as Culture and the law-merchant materials on authority-based trust.