Much of the Quran focuses on a single idea: Islamic monotheism. While Christianity and Judaism also affirm the doctrine of monotheism, Islam is different. The Quran spells out this idea clearly in Surah 6. There are no deities besides Allah alone that govern the entire cosmic order. Hence, Allah sovereignly determines who he guides on the right path and who he leads into error (6:39, 125). Also, if Allah afflicts a person, no one else can remedy it (6:17). For every prophet Allah appointed, he also appointed human and spiritual enemies for the prophet (6:112). These ideas convey that Allah alone governs the universe as He sees fit. Indeed, verse 102 explicitly puts it like this:

Surah Al-Anaam, Verse 102:
ذَٰلِكُمُ اللَّهُ رَبُّكُمْ لَا إِلَٰهَ إِلَّا هُوَ خَالِقُ كُلِّ شَيْءٍ فَاعْبُدُوهُ وَهُوَ عَلَىٰ كُلِّ شَيْءٍ وَكِيلٌ

That is Allah, your Lord, there is no god but He; the Creator of all things, therefore serve Him, and He has charge of all things.