The Heights - 7:75
"The arrogant elders of his people said to the believers whom they humiliated and persecuted, "How do you know that Salih is indeed sent from his Lord?"They said: "We believe in the message he has brought"."
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.