From Pope Benedict XVI's General Audience Catecheses on the Apostle Thomas. Image is from a study guide on the talks by Amy Welborn, available as a free download here.
The Apostle Thomas' case is important to us for at least three reasons: first, because it comforts us in our insecurity; second, because it shows us that every doubt can lead to an outcome brighter than any uncertainty; and, lastly, because the words that Jesus addressed to him remind us of the true meaning of mature faith and encourage us to persevere, despite the difficulty, along our journey of adhesion to him.
A final point concerning Thomas is preserved for us in the Fourth Gospel, which presents him as a witness of the Risen One in the subsequent event of the miraculous catch in the Sea of Tiberias (cf. Jn 21: 2ff.).
On that occasion, Thomas is even mentioned immediately after Simon Peter: an evident sign of the considerable importance that he enjoyed in the context of the early Christian communities.
Indeed, the Acts and the Gospel of Thomas, both apocryphal works but in any case important for the study of Christian origins, were written in his name.
Lastly, let us remember that an ancient tradition claims that Thomas first evangelized Syria and Persia (mentioned by Origen, according to Eusebius of Caesarea, Ecclesiastical History 3, 1) then went on to Western India (cf. Acts of Thomas 1-2 and 17ff.), from where also he finally reached Southern India.
Let us end our reflection in this missionary perspective, expressing the hope that Thomas' example will never fail to strengthen our faith in Jesus Christ, Our Lord and Our God.