For the disciples it must have been hard for them to see the significance of the resurrection. Here they were behind locked doors for fear of the Jews. It wasn't until Jesus came to them on His 3rd appearance after the resurrection that He brought a message of peace. "Peace to you," He said. This was a common greeting that the Jews recognized. "Shalom alechem," peace one to another. Jesus repeats this twice. There is no guilt given for their desertion, confusion or unbelief. Jesus encourages them to go preach the gospel to the world. He would encourage His disciples to believe in Him as their resurrected Lord and Savior.
Thomas was not present for this appearance of Jesus, but eight days later is demanding that he see the marks on the hands and the piercing of His side from the spear. Here Jesus loves the unlovable and tolerates the unbelief because His mission is to win the lost. "My Lord and my God," Thomas says, giving us the highest confession of faith in Jesus seen anywhere in the Scriptures. "My Lord and my God," not just Messiah, Teacher, Rabbi, but Jesus the Christ, God the Son. The confession of faith of Thomas marks the confession of faith of the Christian Church for 2,000 years. Using the title reserved for Almighty God in the Old Testament, "Adonai," Thomas cries out a confession of faith that settles the issue of his doubt.
Did your belief in God come as a result of a doubting heart? Do you suppose it is better to have a nominal belief system that is never challenged by doubt and unbelief? Remember, Jesus loves us enough to never give up on us, and loves us through our doubt and skepticism. Love suffers long.