As for his appeal to the words:

“Those who say, ‘Allah is the third of three,’ have certainly disbelieved.”
[al-Mā’idah: 72]

Some people adopt this approach. They say that His words, Exalted is He:

“Those who say, ‘Allah is the Messiah, son of Mary,’ have certainly disbelieved.”
[al-Mā’idah: 17]

refer to one of their three doctrines: that of the Jacobites, who say that the divine and human natures became a single substance, like water mixed with milk.

And His words:

“The Christians say, ‘The Messiah is the son of Allah.’”
[al-Tawbah: 30]

refer to the doctrine of the Melkites. His words, “The third of three,” refer to the doctrine of the Nestorians, who affirm indwelling—namely, their doctrine of the three hypostases.

The matter is not as these people claim. Rather, what Allah, Exalted is He, mentions is the doctrine of the Christians as a whole. They say that he is God in one respect and the son of God in another.

The intended meaning of His words, “Allah is the third of three,” is indicated by His words:

“O Jesus, son of Mary, did you tell people, ‘Take me and my mother as two gods besides Allah’?”
[al-Mā’idah: 116]

Thus, they worshipped Christ and his mother alongside Him, making Him the third of three in this respect.

As for his statement concerning the Ashʿarīs—that if they say that the One possessing the attributes subsists independently, while the attributes subsist in Him, they have necessarily posited a substance and an accident—this is the same kind of objection as his claim that their position entails His being a body.

They may reply to him: “This also follows from your saying that He is living, knowing, and powerful. For a living, knowing, and powerful being subsists independently. If everything that subsists independently is a substance, then He is a substance; otherwise, your objection fails.”