John 8:24-29
24 But Thomas, one of the twelve, called Didymus, was not with them when Jesus came. 25 The other disciples therefore said unto him, We have seen the LORD. But he said unto them, Except I shall see in his hands the print of the nails, and put my finger into the print of the nails, and thrust my hand into his side, I will not believe. 26 And after eight days again his disciples were within, and Thomas with them: then came Jesus, the doors being shut, and stood in the midst, and said, Peace be unto you. 27 Then saith He to Thomas, Reach hither thy finger, and behold my hands; and reach hither thy hand, and thrust it into my side: and be not faithless, but believing. 28 And Thomas answered and said unto him, My LORD and my God. 29 Jesus saith unto him, Thomas, because thou hast seen Me, thou hast believed: blessed are they that have not seen, and yet have believed.
This shows that doubts are normal and Jesus did not consider it a mortal sin. Wanting proof is normal.
The other apostles would have aleady believed and had faith because they lived with Jesus on a daily basis and saw all his miracles. Thomas too despite the same experience still doubted and was given proof by Jesus himself.
Are we not allowed the same having never seen or experienced a single thing?
"blessed are they that have not seen, and yet have believed" is no more a law or requirment than is "Blessed are the poor in spirit". Again we are being asked to have faith in the faith of Thomas who lived 2,000 years ago. (if that is even true)
More second hand stories.