Faith.

Surah Al-Kahf, Verse 14:

وَرَبَطْنَا عَلَىٰ قُلُوبِهِمْ إِذْ قَامُوا فَقَالُوا رَبُّنَا رَبُّ السَّمَاوَاتِ وَالْأَرْضِ لَن نَّدْعُوَ مِن دُونِهِ إِلَٰهًا لَّقَدْ قُلْنَا إِذًا شَطَطًا

And We strengthened their hearts with patience, when they stood up and said: Our Lord is the Lord of the heavens and the earth; we will by no means call upon any god besides Him, for then indeed we should have said an extravagant thing.