In the plan of the church, there are seven nave windows recessed into the thick masonry walls. Each, of these windows, is a fabrication of bits of glass imported from England and France before the war, as well as, the more recent domestic products. The scenes are portrayed against a lighter background, outlined with a multi-colored bordering. The background is designed in quiet simplicity, to conform to the simple English Gothic origin of the building. It maintains sufficient translucence for lighting purposes, during the daytime. At the same time, its slight opaqueness emphasizes the medallions that tell the various stories with a galaxy of colors, in terms of beauty and poignancy. Each window endeavors to tell a story that would appeal to the various groups and stated of the parishioners. For example, there is the Children's window, donated by the children of the parish, in which the gentle Christ is seen blessing the children. To its left, is the Wedding Feast of Cana, having its motif for the married. The sick, the aged, and the infirm find their counterpart in a scene revealing the compassion of the Divine Physician for the afflicted. The doctrinal message, of the Eucharistic Presence and the Resurrection, are combined in an idealism of color in the scene of Christ and His two disciples, at Emmaus. The subject portrayed in the window, selected by the Bishop, is a scene in which St. Peter, the Prince of the Apostles, is baptizing his disciple, St. Mark, the Evangelist, after whom the parish has been named.
When one rises to leave the church, his eyes are at once drawn to the startling vision of Christ the King, raised high on the west wall in scintillating garments of red against a background of celestial blue and surrounded with the endless signs of the zodiac studded like individual jewels. Immediately, over the door is the apocryphal figure of the Winged Lion with the simple lettering, "St. Mark," at his feet. The beautiful story of the Angelus rings out in the Annunciation window, and the Mystery of the Incarnate Word is told by the Nativity window.
Thus, we find in St. Mark's beautiful window a story is told with two of life's toughest substances, lead – baseless, and glass – scintillating, brilliant. Together, with God's own sun beaming down on them, they become jewels, likened to the rarest diamonds, rubies, and sapphires.