v. 29 Jesus said to him [Thomas], "Have you believed because you have seen me? Blessed are those who have not seen and yet have come to believe."
That would be us. And our countless ancestors for some 2,000 years. All those who have not seen and yet have come to believe.
St. Thomas' Day is an intrusion in the waning days of Advent. Here we are trying to get ready for Christmas and we are aked to contemplate an Easter story. And is it wise to think of doubt at this time of year? The uncomfortable juxtaposition has caused some churches to move this feast to July 3, about as far away from Christmas as you can get. We've kept it here.
But I think St. Thomas does have something to do with Christmas. What Thomas asked for was an incarnation. If he was to believe in the resurrection he needed to see it in the flesh.
Christian faith--even Easter faith--depends on the Incarnation, the enfleshment of God in Jesus Christ. Of course, we don't get to see that. Jesus is gone from us. But he is still enfleshed, and not just in heaven. He is enfleshed in us, his brothers and sisters, who have received the Holy Spirit and so are called his Body. In one sense, every baptism is a little Christmas as well as a little Easter.
We are given one another "in the flesh" to bring about the miracle of faith. If I can see God born in you than I can believe God born in me.