Verrocchio created Christ and Saint Thomas for the central niche on the most important east facade of Orsanmichele. It was the only niche that did not belong to a guild. It was originally assigned to the pro-papacy Guelph party. Having supported the merchant class against the landed aristocracy, the Guelphs were represented at Orsanmichele as the party of the guilds. In 1427 Donatello completed a gilded bronze statue of Saint Louis of Toulouse, the patron saint of the Guelphs, and designed its niche. As Medicean power rose in the second half of the fifteenth century, the Guelph party's importance waned, and it was most probably Medici influence that, in 1462, persuaded the party to sell its prominent niche at Orsanmichele to the Mercanzia, a body that regulated the guilds and served as a merchants' court. The Guelphs removed their statue, and the Mercanzia commissioned from Verrocchio the Christ and Saint Thomasto go in Donatello's niche. Verrocchio seems to have received the commission by the beginning of 1467, and the figure of Christ was modeled and ready for casting by August of 1470. Work must have proceeded slowly: the statue of Christ was cast by 1476 and finished by 1479. Verrocchio probably started modeling the second figure, Saint Thomas, only in 1476, ten years after he had received the original commission; casting took place in 1479, and the bronze was still being cleaned in 1480. A financial dispute in 1481 stopped work on the nearly completed sculpture group until April 1483. Finally, on June 21, 1483, Christ and Saint Thomas was installed in the niche at Orsanmichele. It was an immediate success. On the day of the unveiling a contemporary Florentine, Luca Landucci, wrote in his diary: "It is the most beautiful thing and the most beautiful head of Christ ever made."
The story of the incredulity of Saint Thomas is narrated in John 20:24-29. When Thomas was told by the other apostles that they had seen Jesus, he replied that he would not believe them unless he could see for himself the marks of the nails on Christ's hands and put his hand in the wound on his side. Jesus appeared to all twelve apostles eight days later and exhorted Thomas to put his hand in the wound on his side and to believe. Upon doing this Thomas exclaimed: "My Lord and my God and Savior of the people." These words, in a slightly modified version from the Latin vulgate Bible, are inscribed on the border of the tunic of Verrocchio's Saint Thomas: TV ES DOMINVS MEVS ET DEVS MEVS ET SALVATOR GENTIVM. Christ's reply, "Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed," is on the border of his own tunic: QVIA VIDISTI ME THOMA CREDIDISTI BEATI QVI NON VIDERVNT ET CREDIDERVNT.
The words spoken by the two protagonists serve to underscore the drama of what we see: Thomas moving forward to touch the wound while Christ holds his tunic open with his left hand and blesses Thomas with his right. The dynamic complexity of the action is heightened by Thomas' placement on the outside ledge of the niche. This brilliant innovation, unique at Orsanmichele, also allows more room for Thomas. The issue of limited space in the niche was important, and Verrocchio further addressed it by casting the two figures without backs, like very thick high reliefs. None of the other statues at Orsanmichele are conceived in this way and, once again, Verrocchio demonstrated his inventiveness. It is a mark of the artist's genius that, far from being limited by the physical constraints of the niche, he was inspired to technological and stylistic innovations that brought narrative drama to Orsanmichele for the first time. The niche is no longer a mere container for the sculptures, but becomes rather the frame of reference for Thomas' movement toward Jesus.
The Mercanzia seems not to have had an official patron saint, but the incredulity of Saint Thomas was a very appropriate subject for a merchants' court since, in the fifteenth century, it was typically associated with justice and, specifically, the truth sought by Thomas and the clemency of Jesus. The Medici seem to have been particularly fond of Saint Thomas; since both Piero de' Medici and, later, his son Lorenzo were on the committee in charge of the commission, their influence was probably also at work. The subject must have appealed to the guilds in general, since it placed a statue of Christ on the most important pilaster of Orsanmichele -- as if, appropriately, in charge of the saints.
For the casting of powerful and monumental figures in bronze, Verrocchio must have looked back to Ghiberti's giants, while for the placement of multiple figures in a single niche he must have had in mind Nanni's unique precedent. Benefiting from the lessons of both of his predecessors, in Christ and Saint Thomas Verrocchio introduces moving narrative drama that, in turn, brilliantly foreshadows sculptural developments that would only become fully realized later on in the baroque period