Letter 54

Isidore of PelusiumUnknown|isidore pelusium
From: Isidore of Pelusium, monk
To: An inquirer
Date: ~410 AD
Context: Isidore warns against the heresy of Montanus.

Even if the blasphemy of Montanus was unknown to you until now, as you wrote, it is ancient and extensive, having caused much corruption — both contagion and ruin. You must flee from it headlong and reject it utterly, for it has the power to inflict as much damage on the soul as the founder of the delusion himself discovered when he met the punishment his error deserved. False prophecy is a disease that feeds on attention. Starve it, and it dies.

Modern English rendering for readability. See the 19th-century translation or original Latin/Greek for scholarly use.