‘But Thomas, one of the twelve, called Didymus, was not with them when Jesus came. The other disciples therefore said to him, “We have seen the Lord.” But he said to them, “Unless I see in his hands the print of the nails, and put my finger into the print of the nails, and put my hand into his side, I will not believe”.'
Thomas had missed out on that first appearance of Jesus and when he arrived back and was told about it he was understandably sceptical. They ‘went on telling him' (imperfect tense) how they had seen the nail prints and the wound in His side (John 20:20) and he had retorted in exaggerated fashion that unless he could actually prove it, by himself touching them, he would not believe. Awkward people sometimes take up awkward stances, and the more people try to persuade them the more they react.
The incident is the more emphatic because John has not previously dwelt on the unbelief of the disciples in response to the resurrection although the other Gospels had made quite clear that news of Jesus resurrection was constantly responded to by doubt and unbelief (Luke 24:11; Luke 24:37; Luke 24:41; Mark 16:14), as indeed we would expect.