The Believers - 23:71
If the truth had followed their desires, the heavens and the earth and all that is in them would have fallen into chaos. Yet We gave them their Message, but most of them turn away from it.
The only truth is that God is the only God. If the truth were as they desire, that is, if there were other Gods, the heavens and the earth and all that is in them would be thrown into chaos because of the conflict between the Gods:
The Prophets/21:22
Had there been gods other than Allah in those two (the heavens and the earth), both would have fallen into chaos. Allah, the Owner of absolute authority, is far from their characterizations.
The Believers/23:91
Allah has not begotten a child, nor is there a god with Him. Otherwise, every god would have declared his independence with his creations and would have competed with each other for power. Allah is far away from what they describe.
Luqman/31:30
For Allah is the Truth, and what they call besides Him is falsehood, and Allah is the Most High and the Greatest.