The Stories - 28:47
"So that when a calamity befalls them because of what their own hands have wrought, they may not be able to say: "Our Lord, if you had sent us a messenger, we would have followed your verses and been of the believers"..."
The most important criterion of belief:
The Cattle/6:82
Those who believe and do not mix their faith with wrongdoing, they deserve security and they have found the truth.
Luqman/31:13
"When Lokman advised his son, he said: "My dear son, do not associate partners with Allah; surely shirk (associating partners with God) is a great wrong."
The Companies/39:65
It has been revealed to you and those before you that if you associate partners, all that you do will be in vain and you will be of the losers.