The subject of this painting is taken from the Gospels (John 20:24–28). The scene depicts the moment when Thomas, seeking proof of the Resurrection, places his fingers in the wound in Christ’s right side. This work has been ascribed to Matthias Stom’s Sicilian period, when he combined certain northern European stylistic qualities -for example, the accurate folds of the robes and the expressiveness of the hands- with characteristics of Neapolitan painters of the Seicento. Indeed, the figure types, with their accentuated coarseness, yellow flesh tones, naturalistic modelling of bodies and faces, which are painted with a heavily loaded brush, and the marked contrasts of darkness and light attest to Stom’s assimilation of the style of the followers of Ribera. Stom may have met Ribera and studied his work when in Naples.

Although the iconography of this scene can be traced back to Caravaggio’s Doubting Thomas, 1602-03 (Sanssouci Palace, Potsdam, Germany), Stom appears to have based his composition on two slightly later paintings of this subject. First, he follows Hendrick ter Brugghen’s Doubting Thomas, c.1621-23 (Rijksmuseum, Amsterdam), which inverts Caravaggio’s composition to position Saint Thomas on Christ’s right side, preventing the Apostle from stretching his arm across Jesus’s body. But Stom mainly based his work on Rubens’s Incredulity of Saint Thomas, 1613-15 (Royal Museum of Fine Arts, Antwerp), commissioned by the burgomaster Nicolaas Rockox between 1613 and 1615 for the Immaculata Chapel, sponsored by Rockox in the church of Antwerp’s Minorite Recollects, in 1619-20. In Stom’s painting the naked torso of Christ is indisputably the main focus of attention, as it is in Rubens’s, but not in either Caravaggio’s or ter Brugghen’s compositions.

As in Rubens’s work, this prominence is underscored by the gesture of Christ opening his arms to allow full view of his torso, while his body leans slightly backwards, away from the group of Apostles to his side. Also, the powerful lateral lighting transforms the torso into a source of light, which in turn illuminates the scene. This transformation of Christ may relate both to his state as a luminous resurrected body -which would explain why neither the nail holes in his hands nor the wounds from the crown of thorns on his forehead are shown- and to the new meaning of the Corpus Christi in Counter-Reformation doctrine.

The inventory of the paintings saved from the fire at the Alcázar Palace, Madrid, in 1734 registers this painting as a copy of an original by Guercino, whereas the 1772 inventory of the Royal Palace in Madrid describes it as an original by Gerard van Honthorst. This attribution was retained in the Museo del Prado’s catalogues until 1963, when it was reattributed to Hendrick ter Brugghen (1588-1629). Finally, in the 1958 catalogue it is recorded as a work by Matthias Stom, an attribution proposed many years before by Arthur von Schneider and ever since unanimously accepted.

In the Baron Scotti collection in Bergamo there is one other version of this subject by Stom, which is also dated to the painter’s Sicilian period.

Posada Kubissa, Teresa, Mathias Stom 'The incredulity of Saint Thomas'. En: Italian masterpieces from Spain's royal court, Museo del Prado, National Gallery of Victoria Thames & Hudson, 2014, p.144