My holy book says my holy book is true
Some apologists are we can know their holy book is true based on the claim in the holy book that it is true. This is a circular argument.
"All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:"
"Indeed, the religion in the sight of Allah is Islam. And those who were given the Scripture did not differ except after knowledge had come to them - out of jealous animosity between themselves. And whoever disbelieves in the verses of Allah , then indeed, Allah is swift in [taking] account."