The Christians are a community upon whom misguidance—whose root is ignorance—is inevitable. Never has there been anyone who is Christian both inwardly and outwardly without being astray and ignorant regarding the One he worships and the foundations of his religion: he does not know whom he worships, nor the manner in which he should worship, despite whatever effort some of them expend in devotion, asceticism, and fine moral conduct.

Concerning these people it is said:
• Their statement: “two natures”;
• and they also say: “He has two wills”;
• and they further say: “He is a single person; his number has not increased.”

For they assert, “the two have united,” as they record in this very book of theirs; they refuse to acknowledge two persons lest they be forced to speak of four hypostases.

Some of them maintain, “They are two substances,” while others say, “a single substance.”

If they claim, “It is one substance,” their view is of the same order as that of the Jacobites—especially since they also assert, “Mary gave birth to the divinity and the humanity, and that ‘the Messiah’ is a name encompassing both divinity and humanity; he is perfect God and perfect man.”

Yet if it is indeed a single substance, it necessarily entails that the divinity has been transformed and altered, and likewise the humanity; for when the two become a single entity, that third entity is neither pure man nor pure God. Rather, humanity and divinity have fused within it, even though man and God had previously been two distinct realities—