Verse 6:19 says Allah is 'ilaahoon waahidoon'. What do you think of this?
قل اي شئ اكبر شهادة قل الله شهيد بيني وبينكم واوحي الي هذا القران لانذركم به ومن بلغ ائنكم لتشهدون ان مع الله الهة اخري قل لا اشهد قل انما هو اله واحد وانني بري مما تشركون
Say (O Messenger), “What could be the greatest witness?” Say, “Allah is Witness between me and you. This Qur’an has been revealed to me so that I may warn you as well as whomever it reaches. Do you bear witness that there are other deities besides Allah?” Say, “I bear no such witness.” Say, “He is the One God. I disown what you associate with Him.”
It may also help you on reflecting on these verses:
2:7 God (His Law of Cause and Effect) has sealed their hearts and their hearing, and on their sight there is a veil. And theirs will be a
2:213 Mankind were one single community (but selfishness divided them). So, God sent prophets as bearers of good news and warnings. He sent down with them the scripture in absolute truth that it might judge between people wherein they differed. But again, out of mutual rivalry, they divided themselves after all evidence of the Right had come to them! So, God shows the lighted road to those who would acknowledge the truth and thus resolve their disputes. And God guides to the straight road him who wills to be guided.
3:4 He has bestowed guidance upon mankind before, and now He has sent the Final Criterion between right and wrong. Those who reject the revelations of God, theirs will be a strict retribution. God Almighty’s Law of Cause and Effect carries all things and actions to their logical outcome.
45:23 Have you ever noted him who makes his desires his god? Consequently, God lets him go astray despite his knowledge, seals up his hearing and his heart, and places a veil on his sight. Then who will lead him after he has left God? Will you not then remember (this admonition)?