The association of various panels in the form of small, easily transportable altarpieces was already common in the 15th century, but since the Council of Trent (1545-1563) they have renewed their iconographic programme. Among the most common themes are the Passion cycle, with the climax of the Crucifixion, as well as the lives of saints. The spirit of the Counter-Reformation sought to stimulate people's feelings in order to project religious experiences outside the churches. Thus, a large number of private altars or domestic oratories were built on the walls and in the chapels of houses to express the piety of their inhabitants. The most common are triptychs of three panels, decorated both internally and externally, with the side panels serving as closing doors.
In the central panel, Christ Crucified follows a model similar to that of the Toledo school of painting, which is why the panel has come to be attributed to Luis Tristán, a disciple of El Greco. In the upper part of the central image the sun is partially hidden on the left, while the moon appears on the right, evoking the darkness that covered the earth when Christ expired. At the foot of the cross, a skull symbolises the legend according to which Adam would have been buried on Golgotha, in the same place where the cross was raised. The upper left panel depicts Saint Joseph holding a flowering rod and a carpenter's square. Next to him, the infant Jesus in light blue holds an orb as "Salvator Mundi", a symbol of his divinity. Below them is Saint John the Baptist, standing barefoot and half-naked, wearing a nimbus and holding in his right hand a staff topped with a cross. At his feet is a lamb lying with a halo as a precursor and messenger of Christ. In the upper right panel Saint Michael, holding a shield, thrusts a spear into a winged demon lying on the ground, which he treads on with both feet, a scene that alludes to the battle between Saint Michael the Archangel and Satan. Below, Saint Bruno, wearing the white habit of the Carthusians with a nimbus and a crozier lying at his feet, symbolising his contempt for the hierarchies of this world.
Technically, two supports are combined in a very original way: oil on canvas for the central scene and oil on panel for the sides. The frames are richly gilded and decorated with floral motifs created with the estofado technique (from the original period) and others painted (a posteriori). The back is painted in oil and features a composition of geometric motifs on a grey background, creating a play of light and shadow that seeks architectural perspectives by imitating marble such as green serpentine and other hard stones such as striated red jasper or granite of various colours.