Damasus spoke out against major heresies (including Apollinarianism and Macedonianism), thus solidifying the faith of the Catholic Church, and encouraged production of the Vulgate Bible with his support for Jerome.

It has been suggested that Damasus or another of the group commissioned and distributed these to friends or supporters, as part of a programme "insistently inserting his episcopal presence in the Christian landscape".

The reign of Gratian, which coincided with Damasus' papacy, forms an important epoch in ecclesiastical history, since during that period (359–383), Catholic Christianity for the first time became dominant throughout the empire.

While this simple method worked well in a small community of Christians unified by persecution, as the congregation grew in size, the acclamation of a new bishop was fraught with division, and rival claimants and a certain class hostility between patrician and plebeian candidates unsettled some episcopal elections.

[13] Thomas Shahan says details of this scandalous conflict are related in the highly prejudiced "Libellus precum ad Imperatores" (P.L., XIII, 83–107), a petition to the civil authority on the part of Faustinus and Marcellinus [ru], two anti-Damasan presbyters.

This account also records that an armed force instigated by Damasus broke into the Basilica of Julius and a three-day slaughtering of those assembled there took place.

Damasus then responded by ordering an attack against the Liberian basilica, resulting in another massacre: "They broke down the doors and set fire underneath it, then rushed in...and killed a hundred and sixty of the people inside, both men and women."

[20] One of the important works of Pope Damasus was to preside in the Council of Rome of 382,[21] which determined the canon or official list of Sacred Scripture.

It is now commonly held that the part of the Gelasian Decree dealing with the accepted canon of Scripture is an authentic work of the Council of Rome of 382 A.D. and that Gelasius edited it again at the end of the fifth century, adding to it the catalog of the rejected books, the apocrypha.

Invited to Rome originally to a synod of 382 convened to end the schism of Antioch, he made himself indispensable to the pope, and took a prominent place in his councils.

Writing in 409, Jerome remarked: "A great many years ago when I was helping Damasus, bishop of Rome with his ecclesiastical correspondence, and writing his answers to the questions referred to him by the councils of the east and west..."[25] In order to put an end to the marked divergences in the western texts of that period, Damasus encouraged the highly respected scholar Jerome to revise the available Old Latin versions of the Bible into a more accurate Latin on the basis of the Greek New Testament and the Septuagint, resulting in the Vulgate.

There is a current friendly to them, another one distinctly unfavourable to their authority and sacredness, while wavering between the two are a number of writers whose veneration for these books is tempered by some perplexity as to their exact standing, and among those we note St. Thomas Aquinas.

[27]Significant scholarly doubts and disagreements about the nature of the Apocrypha continued for centuries and even into Trent,[28][29][30] which provided the first infallible definition of the Catholic canon in 1546.

But since by reason of my sins I have betaken myself to this desert which lies between Syria and the uncivilized waste, I cannot, owing to the great distance between us, always ask of your sanctity the holy thing of the Lord.

[35]The Eastern Church, in the person of Basil of Caesarea, earnestly sought the aid and encouragement of Damasus against an apparently triumphant Arianism.

[14] Damasus also did much to encourage the veneration of the Christian martyrs,[39] restoring and creating access to their tombs in the Catacombs of Rome and elsewhere, and setting up tablets with verse inscriptions composed by himself, several of which survive or are recorded in his Epigrammata.

[40] Damasus rebuilt or repaired his father's church named for Laurence, known as San Lorenzo fuori le Mura ("St Lawrence outside the walls"), which by the 7th century was a station on the itineraries of the graves of the Roman martyrs.

Damasus' regard for the Roman martyr is attested also by the tradition according to which the Pope built a church devoted to Laurence in his own house, San Lorenzo in Damaso.

[41] Since 2011, this saint has given its name to the San Damaso Ecclesiastical University, a Catholic center of higher education belonging to the Archbishopric of Madrid, in Spain, where theology, Canon Law, Religious Sciences, Christian and Classical Literature, and Philosophy can be studied.