Part of his output during this period included a major set of annotations on the Pentateuch, titled Veteris testamenti ad Hebraicam veritatem recognitio, in which he used Hebrew and Greek manuscripts from the Grimani Library to correct Jerome's Vulgate translation of the Old Testament text.
[3] Steuco believed that Roman Catholicism, centred on the Gospels, is the true hidden core of pagan beliefs; Theobald Freudenberger commented that "If a [ancient] passage really refuses to fit into his system, he earnestly addresses the author and admonishes him in a fatherly way to come to his senses.
"[4] This work has a slight polemical edge to it, as Steuco crafted a number of his arguments to lend support to several theological positions that had recently come under question in Italy by reformers and critics of the traditional Catholic faith.
In this historical/religious context, Steuco’s work comes to assume the significance of a desperate last attempt, effected by the means of historical erudition, of reuniting and reconciling the fragmented Christian world ... [It] represents perhaps one of the last attempts to utilize the Humanist ideals in the interest of Catholic Reform, before the latter “will yield to the disciplinary and dogmatic force of the Counter-Reformation, which will preserve from Humanism only the splendid but henceforth empty outer form.”As a Roman humanist, he also took a deep interest in the classical ruins of Rome, and in the urban renewal efforts of Paul III throughout the city.
Of particular note in this vein are a series of short orations that he wrote and possibly delivered at the papal court, urging Paul III to refurbish the aqueduct known as the Aqua Virgo, in order to supply Rome with adequate fresh water, and as a major key to the revitalization of the city itself.