the Christians go astray for any reason other than that they seized upon the ambiguous statements of the prophets and neglected the clear ones?

Second: one must show that such a contention is unfit to oppose what the prophets have brought. So if certain people begin to disparage some aspect of the revealed laws on the basis of personal opinion, it is made plain to them that whatever is soundly established from the prophets cannot be countered by opinion or by analogy.

Third: the defect of that rational claim itself must be exposed.
If it belongs to the realm of informative propositions, its flaw is laid bare—as we have set out in detail in our book Darʾ Taʿāruḍ al-ʿAql wa’l-Sharʿ (Repelling the Conflict Between Reason and Revelation). There we clarified that every rational proof marshalled against the prophetic texts is invalid, and we listed the chief arguments on which the negators rely in this matter.
If, however, it falls under the category of prescriptive propositions—that is, commands and prohibitions—then whoever