What should we do with the elder sheikhs who do not believe in the miraculousness of the Qur’an?

The facets of miraculousness (I'jaz) in the Quran are numerous and varied. However, a Muslim is only obligated to believe that the Quran is the perfect word of Allah, to which falsehood cannot approach, and that it is the greatest miracle of the Prophet Muhammad, peace be upon him. As for what is called "scientific I'jaz," it is not obligatory to believe in it. Its indications are speculative and a matter of scholarly interpretation; some may find comfort in them, but they should not be relied upon to prove that the Quran is true, because it does not need them. The Quran is true in its essence; its news is truth, and its rulings are justice. Whatever facts align with the Quran are established, and whatever contradicts it is false.