'Unbelief' in the Bible

And he did not do many miracles there because of their unbelief.

And he was amazed because of their unbelief. Then he went around among the villages and taught.

Immediately the father of the boy cried out and said, "I believe; help my unbelief!"

Then he appeared to the eleven themselves, while they were eating, and he rebuked them for their unbelief and hardness of heart, because they did not believe those who had seen him resurrected.

Then he said to Thomas, "Put your finger here, and examine my hands. Extend your hand and put it into my side. Do not continue in your unbelief, but believe."

What then? If some did not believe, does their unbelief nullify the faithfulness of God?

He did not waver in unbelief about the promise of God but was strengthened in faith, giving glory to God.

Granted! They were broken off because of their unbelief, but you stand by faith. Do not be arrogant, but fear!

And even they -- if they do not continue in their unbelief -- will be grafted in, for God is able to graft them in again.

even though I was formerly a blasphemer and a persecutor, and an arrogant man. But I was treated with mercy because I acted ignorantly in unbelief,

So we see that they could not enter because of unbelief.