Before we criticize the unbelief of Thomas, let’s try to put ourselves in his shoes.
Have you ever had one of your friends come back from seeing a movie; or going to a concert; or visiting a beautiful place; and the friend says to you, “You have GOT to see this!” You listen with interest, even as you try to figure out between what’s hype and what’s real. To know what you believe about what they are reporting, you’ll just have to go see the movie yourself, or try the product, or see the sunset in that particular spot. In order to offer your own testimony, you’re going to need to have your own experience. John, the Gospel writer knows this. His entire gospel exhibits a pattern in which someone hears about Jesus and needs more, and then receives what they need to come to their own experience of the life Jesus is embodying in the world.