Exactly what Thomas asked

Thomas didn't believe that the others had seen the risen Jesus. He had told them exactly what he needed: his finger in the nail wounds, his hand in the side. Jesus wasn't there then. Yet now he repeats almost word for word what Thomas said. So he had heard the doubt.

His last sentence can also be read as: do not become faithless, but believing. Then faith isn't a label you either have or don't have. It is a direction you grow in. John doesn't tell us, by the way, whether Thomas actually touched Jesus.