The Cow - 2:214
"Or do you think that you will enter Paradise until the like of what happened to those before you befalls you? They suffered hardship and distress and were so shaken that the apostle and those who believed with him said, "When is the help of Allah?"Know well that Allah´s help is near."
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.