Jesus said to Thomas, “Have you believed because you have seen me? Blessed are those who
have not seen and yet have believed." - John 20:29
Many have seen this as a teaching that we ought to have blind faith, and that seeking evidence is contrary to Christianity. Reading the next couple lines dispels this notion:
“Now Jesus did many other signs in the presence of the disciples, which are not written in this book; but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.”
If we ought to believe blindly, why did John say that the very purpose of his book is that we might believe based upon the evidence of miracles? It is much more likely that Jesus’ comment to Thomas referred to the fact that he continued to disbelieve even after he had evidence.
Jesus did not say that Thomas had sinned in asking for evidence. Jesus did not say that those who saw his miracles as verification of his divinity were sinning in doing so. The corrections made by Jesus and the New Testament writers were never for those who sought evidence, but rather for those who denied the evidence, or demanded an unreasonable level of proof.