The Heights - 7:157
Indeed, they follow (when the time comes) that messenger whom they find written in the Torah and the Gospel with them, the Messenger of Allah, the Messenger of the Ummim (who has not read the Torah and the Gospel), who enjoins upon them good and forbids them from evil, who makes lawful for them good things and forbids for them unclean things, who removes from them the weights and the fetters that weigh them down. Those who believe in him and respect him and help him and follow the light sent down with him are the successful ones.
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.