This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Christianity reached the territory that is now Austria long before any Austrian state existed to call it a national church. Roman-era Christian communities are recorded from around 174 AD, and by 304 AD the martyrdom of Saint Florian and forty companions at Lauriacum, during the persecution under Diocletian, is dated with enough precision to mark a settled Christian presence rather than a scattered one. Saint Severin worked as a missionary along the Danube until his death in 482, and Bavarian Christianization of the western territories followed, establishing the monasteries that would anchor the region's church life through the disruptions of the following centuries.
The diocesan structure that still shapes the Church in Austria today has a specific founding point: Saint Rupert founded the diocese of Salzburg around the turn of the eighth century, and Salzburg became an archdiocese in 798, serving as the starting point for Christianizing the east and south of the Austrian lands alongside the diocese of Passau. Vienna itself did not become a separate bishopric until 1469, more than six and a half centuries after Salzburg. Today the Church in Austria is organized under two archdioceses, Vienna and Salzburg, the latter's archbishop holding the historic title Primus Germaniae, primate of Germany, even though Austria itself has no archbishop formally styled a primate.