We all struggle with a measure of unbelief, but the good news is that we can also grow from faith to faith. I love this honest response of a desperate father, pleading for Jesus to heal his tormented son. When asked by Jesus if he could believe, he humbly declares, "Lord, I believe, but help my unbelief."
In another account, Thomas doubted the testimony of the other disciples regarding Jesus. He stated he needed to see to believe, that his belief was anchored by his external senses of perception. Instead of scolding Thomas for his lack of faith, Jesus did not withhold any evidence and patiently obliged Thomas by giving him all he needed to move from unbelief to belief in his heart.
God doesn't reject the skeptical, it's us who do that. So if you need more faith to see the impossible, just ask Him.
(Mark 9:23-27 NKJV)
23 Jesus said to him, “If you can believe, all things are possible to him who believes.”
24 Immediately the father of the child cried out and said with tears, “Lord, I believe; help my unbelief!”
25 When Jesus saw that the people came running together, He rebuked the unclean spirit, saying to it: “Deaf and dumb spirit, I command you, come out of him and enter him no more!”
26 Then the spirit cried out, convulsed him greatly, and came out of him. And he became as one dead, so that many said, “He is dead.”
27 But Jesus took him by the hand and lifted him up, and he arose.
(John 20:24-29 NIV)
24 Now Thomas (also known as Didymus), one of the Twelve, was not with the disciples when Jesus came.
25 So 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.”
26 A 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!”
27 Then 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.”
28 Thomas said to him, “My Lord and my God!”
29 Then Jesus told him, “Because you have seen me, you have believed;
blessed are those who have not seen and yet have believed.”