Hud 11:14

Fa-illam yastajeeboo lakum faAAlamooannama onzila biAAilmi Allahi waan la ilahailla huwa fahal antum muslimoon

And if they do not respond to you - then know that it [i.e., the Qur’ān] was revealed with the knowledge of Allāh and that there is no deity except Him. Then, would you [not] be Muslims?

So, if they do not respond to your call, then be assured that it has been sent down with the knowledge of Allah and that there is no god but He. So, do you submit?