Bible Verses About Unbelief: Hardness of heart

And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.

Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief.

Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.

Let us labour therefore to enter into that rest, lest any man fall after the same example of unbelief.

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