If Muhammad is God’s final prophet, then he MUST be predicted in the Bible (surah 7:157). Here I will deal with the illiterate person in Isaiah 29:12. In order to understand this verse properly, we need to study the context. The chapter begins with the words ”Ah, Ariel, Ariel, the city where David encamped!” (29:1). Which city is Isaiah referring to? It’s Jerusalem. So the illiterate person in verse 12 is living in Jerusalem and not in Mecca. Let’s jump to 29:11-12:

The vision of all this has become to you like the words of a book that is sealed. When men give it to one who can read, saying, ”Read this,” he says, ”I cannot, for it is sealed.” And when they give the book to one who cannot read, saying, ”Read this,” he says, ”I cannot read.”

What’s going on here? The people in Jerusalem came up with excuses not to listen to the word of God. So God used one literate and one illiterate person to make his point, i.e. to display their excuses not to listen. Note also what it says in the following verse:

The Lord said: ”Because this people draw near with their mouth and honor me with their lips, while their hearts are far from me, and their fear of me is a commandment taught by men.” (29:13)

If you want to apply 29:12 to Muhammad, then you have to do the same with this verse, i.e. Muhammad was honoring God with his lips, while his heart was far from Him. Do you agree? I assume not. In sum: Isaiah 29:12 is talking about people living in Jerusalem in the 8th century BCE, and has nothing to do with an Arab guy who lived in Mecca in the 7th century CE.