Mark 9:17-24
17A man in the crowd answered, "Teacher, I brought you my son, who is possessed by a spirit that has robbed him of speech. 18Whenever it seizes him, it throws him to the ground. He foams at the mouth, gnashes his teeth and becomes rigid. I asked your disciples to drive out the spirit, but they could not." 19"O unbelieving generation," Jesus replied, "how long shall I stay with you? How long shall I put up with you? Bring the boy to me." 20So they brought him. When the spirit saw Jesus, it immediately threw the boy into a convulsion. He fell to the ground and rolled around, foaming at the mouth. 21Jesus asked the boy's father, "How long has he been like this?" "From childhood," he answered. 22"It has often thrown him into fire or water to kill him. But if you can do anything, take pity on us and help us." 23" 'If you can'?" said Jesus. "Everything is possible for him who believes." 24Immediately the boy's father exclaimed, "I do believe; help me overcome my unbelief!"
John 4:50
50Jesus replied, "You may go. Your son will live." The man took Jesus at his word and departed.
John 20:24-31
24Now Thomas (called Didymus), one of the Twelve, was not with the disciples when Jesus came. 25So the other disciples told him, "We have seen the Lord!" But he said to them, "Unless I see the nail marks in his hands and put my finger where the nails were, and put my hand into his side, I will not believe it." 26A week later his disciples were in the house again, and Thomas was with them. Though the doors were locked, Jesus came and stood among them and said, "Peace be with you!" 27Then he said to Thomas, "Put your finger here; see my hands. Reach out your hand and put it into my side. Stop doubting and believe." 28Thomas said to him, "My Lord and my God!" 29Then Jesus told him, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed."
30Jesus did many other miraculous signs in the presence of his disciples, which are not recorded in this book. 31But these are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.
1 Corinthians 1:18-25
18For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. 19For it is written: "I will destroy the wisdom of the wise; the intelligence of the intelligent I will frustrate." 20Where is the wise man? Where is the scholar? Where is the philosopher of this age? Has not God made foolish the wisdom of the world? 21For since in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe. 22Jews demand miraculous signs and Greeks look for wisdom, 23but we preach Christ crucified: a stumbling block to Jews and foolishness to Gentiles, 24but to those whom God has called, both Jews and Greeks, Christ the power of God and the wisdom of God. 25For the foolishness of God is wiser than man's wisdom, and the weakness of God is stronger than man's strength.