Our Saint Apostle Thomas was not someone to take others' testimonies for granted. He desired to see and touch the Resurrected Lord and True God Jesus Christ. That's when he said: "You are my Lord and God".
This is the lesson the Evangelist presents us - taste and see how wonderful and awesome is our Resurrected Lord Jesus Christ - Very God of Very God, Begotten, not made, of one essence with the Father, by Whom all thing were made.
Let us taste and experience God, Who became Man and dwelt with us full of grace and truth!