Final answer:
The argument from incredulity is the most prominent logical fallacy in the claim that the Qur'an's unique style proves the truth of Islam, as it assumes divine origin due to a lack of alternative explanations.
Step-by-step explanation:
The most prominently exhibited logical fallacy in the argument claiming the truth of Islam based on the unique textual style of the Qur'an is the argument from incredulity. This is because the argument relies on the assumption that because one cannot imagine how the Qur'an could have been produced without divine intervention, it must therefore have a divine origin. This type of reasoning fails to consider alternative explanations and leaps to a conclusion based on a lack of understanding or personal incredulity.