The Forgiver - 40:28
"A believing man from Pharaoh´s side who concealed his faith said, "Are you going to kill a man who says, ´My Lord is Allah´? He has brought you clear proofs from your Lord. If he is a liar, that is his problem; but if he is truthful, what he has told you will come true. Surely Allah does not love the liars who transgress."
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.