The Heights - 7:96
If the peoples of the countries had believed and acted righteously, We would have opened for them abundance from the heavens and the earth. But they denied, so We seized them with what they had earned.
The most important criterion for believing in Allah:
The Cattle/6:82
Those who believe and do not mix their faith with wrongdoing, they deserve security and they have found the truth.
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.
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."