Doubting Thomas, we call him to this day, because he did not believe without seeing. He didn't believe it when the other Apostles told him that the Lord was risen.
But when you pay attention, you realize that none of the other Apostles believed what they'd been told about it either. It's John who tells us about Thomas; Luke says, "Now it was Mary Magdalene and Joanna and Mary the mother of James and the other women with them who told this to the Apostles, but these words seemed to them an idle tale, and they did not believe them." Mark, in his succinct way, remarks, "But when they heard that he was alive and had been seen by [Mary Magdalene], they would not believe it."
Now, I don't mean to lump all the Apostles in as unbelievers. I think we get kind of complacent about it, because we (I think all my readers are Christian) have believed that Christ rose from the dead since forever. But if you had seen your friend brutally murdered and then had somebody come back a couple days later and tell you that friend was alive and well, would your first instinct be to say, "Hooray! Let's go declare the good news to the ends of the earth!"? Or would it be to say, "Stop making up stories and leave me alone in my grief."?
And how many of us would be willing (to paraphrase one of my theology professors) to stand up and voice our beliefs to the point of shedding blood? The Apostles might not have believed it until they saw it, but once they did believe they didn't turn back.
Doubting Thomas himself, according to tradition, went all the way to India, where he was eventually martyred--but in the meantime, as the Cobbler put it, he taught those who had not seen to believe.
There is a church there that quite straightforwardly states it was founded by the Apostle in AD 54. (And then adds that the current building is "supposedly" the fourth.) The Christian community there lasted all by itself, a little far-flung island of belief in the Resurrection, for about 1600 years before the Portuguese found it. (And were rather rude about things, by all accounts. Some things definitely don't inspire me with the wonderfullness of us Catholics.)
I'd say Thomas did a pretty good job for a doubter, wouldn't you?
This post would be incomplete if I did not at least mention that today is the feast of another amazing St. Thomas, this one surnamed Aquinas and hailing from the 13th century. I could write a very long, rambly post about everything the Dumb Ox has done for me, but that would take a good long time. (I worked on my Mary post for more than a month, did I tell you that?)