'Unbelief' in the Bible

For what if some did not believe? shall their unbelief make the faith of God without effect?

He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God;

Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:

for if God did not spare the natural branches [because of unbelief], He will not spare you either.

And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again.

For as ye in times past have not believed God, yet have now obtained mercy through their unbelief:

For God hath concluded them all in unbelief, that he might have mercy upon all.