The Victory - 48:26
When those who disbelieved ignited in their hearts anger and bigotry, the fanaticism of the ignorance period, Allah sent down His peace upon His Messenger and the believers and made them keep their promise of righteousness. They were worthy and deserving of it. Allah is All-Knowing.
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.