was traditionally the feast of St. Thomas the Apostle, and in fact still is in my ancient Butler's Lives of Saints in which no saint's feast day ever changes. Now it is celebrated on July 3rd, which, being so close to an American holiday, tends to get sucked into the general fog that secular holidays produce.
As a Thomas, I'm always struck by how few of my fellow so-named consider St. Thomas the Apostle their patronal saint. Thomas has stiff competition given Thomas Aquinas and Thomas More, to name two. But it's very American to like the underdog and St. Thomas the Apostle feels more accessible than Aquinas, (though Thomas More has over the past decade mushroomed in personal significance).
St. Thomas is famous, of course, for not believing when the others said Christ had risen. But I like what Dom Orchard offers in his Scriptural commentary:
A blend of scepticism and pessimism goes with a melancholic temperament, such as seems to have been that of Thomas...The case of Thomas, in whom John [the Evangelist] took a special interest, is very important because, as St. Gregory remarks, the slow surrender of Thomas is of more advantage to strengthen our faith than the more ready faith of all the believing Apostles. Besides, the act of faith made by the believing Thomas is the fullest and most explicit of all the confessions of faith recorded in the Gospels.