4 Bible Verses about Incredulity

But Thomas, one of the twelve [disciples], who was called Didymus (the twin), was not with them when Jesus came.

behold, I will put a fleece of [freshly sheared] wool on the threshing floor. If there is dew only on the fleece, and it is dry on all the ground [around it], then I will know that You will rescue Israel through me, as You have said.” And it was so. When he got up early the next morning and squeezed the dew out of the fleece, he wrung from it a bowl full of water. Then Gideon said to God, “Do not let your anger burn against me, so that I may speak once more. Please let me make a test once more with the fleece; now let only the fleece be dry, and let there be dew on all the ground.” read more.
God did so that night; for it was dry only on the fleece, and there was dew on all the ground [around it].

Then they brought the man who was formerly blind to the Pharisees. Now it was on a Sabbath day that Jesus made the mud and opened the man’s eyes. So the Pharisees asked him again how he received his sight. And he said to them, “He smeared mud on my eyes, and I washed, and now I see.” read more.
Then some of the Pharisees said, “This Man [Jesus] is not from God, because He does not keep the Sabbath.” But others said, “How can a man who is a sinner (a non-observant Jew) do such signs and miracles?” So there was a difference of opinion among them. Accordingly they said to the blind man again, “What do you say about Him, since He opened your eyes?” And he said, “[It must be that] He is a prophet!” However, the Jews did not believe that he had been blind and had received his sight until they called the man’s parents. They asked them, “Is this your son, who you say was born blind? Then how does he now see?” His parents answered, “We know that this is our son, and that he was born blind; but as to how he now sees, we do not know; or who has opened his eyes, we do not know. Ask him [and stop asking us]; he is of age, he will speak for himself and give his own account of it.” His parents said this because they were afraid of [the leaders of] the Jews; for the Jews had already agreed that if anyone acknowledged Jesus to be the Christ, he would be put out of the synagogue (excommunicated). Because of this his parents said, “He is of age; ask him.” So a second time they called the man who had been [born] blind, and said to him, “Give God glory and praise [for your sight]! We know this Man [Jesus] is a sinner [separated from God].” Then he answered, “I do not know whether He is a sinner [separated from God]; but one thing I do know, that though I was blind, now I see.” So they said to him, “What did He [actually] do to you? How did He open your eyes?” He answered, “I already told you and you did not listen. Why do you want to hear it again and again? Do you want to become His disciples, too?” And [at that remark] they stormed at him and jeered, “You are His disciple, but we are disciples of Moses! We know [for certain] that God has spoken to Moses, but as for this Man, we do not know where He is from.” The man replied, “Well, this is astonishing! You do not know where He comes from, and yet He opened my eyes! We know [according to your tradition] that God does not hear sinners; but if anyone fears God and does His will, He hears him. Since the beginning of time it has never been heard that anyone opened the eyes of a person born blind. If this Man were not from God, He would not be able to do anything [like this because God would not hear His prayer].” They answered him, “You were born entirely in sins [from head to foot], and you [presume to] teach us?” Then they threw him out [of the synagogue]. Jesus heard that they had put him out [of the synagogue], and finding him, He asked, “Do you believe in the Son of Man?” He answered, “Who is He, Sir? Tell me so that I may believe in Him.” Jesus said to him, “You have both seen Him, and [in fact] He is the one who is talking with you.” And he said, “Lord, I believe [in You and Your word]!” And he worshiped Him [with reverence and awe]. Then Jesus said, “I came into this world for judgment [to separate those who believe in Me from those who reject Me—to declare judgment on those who choose to be separated from God], so that the sightless would see, and those who see would become blind.” Some Pharisees who were with Him heard these things and said to Him, “Are we also blind?” Jesus said to them, “If you were blind [to spiritual things], you would have no sin [and would not be blamed for your unbelief]; but since you claim to have [spiritual] sight, [you have no excuse so] your sin and guilt remain.

But we would like to hear from you what your views are [that is, exactly what you believe]; for in regard to this sect (Christianity), we are fully aware that it is denounced everywhere.” When they had set a day for Paul, they came to his lodging in large numbers. And he carefully explained [Christianity] to them from morning until evening, solemnly testifying about the kingdom of God and trying to persuade them concerning Jesus, both from the Law of Moses and from the [writings of the] Prophets. Some were persuaded by what he said, but others would not believe. read more.
They disagreed among themselves and they began to leave after Paul had made one last statement: “The Holy Spirit rightly spoke through Isaiah the prophet to your fathers, saying, ‘Go to this people and say,

“You will keep on hearing, but will not understand,
You will keep on seeing, but will not perceive;

“For the heart (the understanding, the soul) of this people has become dull (calloused),
And with their ears they scarcely hear,
And they have shut their eyes [to the truth];
Otherwise they might see with their eyes,
And hear with their ears,
And understand with their heart and return [to Me],
And I would heal them.”’ Therefore let it be known to you that [this message of] the salvation of God has been sent to the Gentiles; they indeed will listen!” [And when he had said these things, the Jews left, arguing among themselves.]