'Unbelief' in the Bible

And He was amazed at their unbelief.Now He was going around the villages in a circuit, teaching.

Immediately the father of the boy cried out, “I do believe! Help my unbelief.”

Later, He appeared to the Eleven themselves as they were reclining at the table. He rebuked their unbelief and hardness of heart, because they did not believe those who saw Him after He had been resurrected.