The Victory - 48:29
Muhammad, the Messenger of Allah, and those who are with him are harsh against the disbelievers and merciful among themselves. You see them bowing down and prostrating themselves, asking Allah for His favor and pleasure. On their faces are the marks of prostration. This is their character in the Torah. And in the Gospel they are like a plant that has sprouted and grown strong and thickened and stood up on its stems, delighting the cultivators. He enrages the disbelievers with them. Allah has promised forgiveness and a great reward to those of them who believe and do righteous deeds.
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.