Saint Paulinus II (c. 726 – 11 January 802 or 804 AD) was a priest, theologian, poet, and one of the most eminent scholars of the Carolingian Renaissance.

Paulinus was born at Premariacco, near Cividale (the Roman Forum Iulii) in the Friuli region of north-eastern Italy, during the latter days of Lombard rule.

Paulinus' educational background prepared him to play a key part in the Carolingian Renaissance, allowing him to capably assist in the promotion of Christendom and the restoration of Western civilization after centuries of unstable barbarian rule.

It was precisely because of his exceptional learning that Paulinus first came to the attention of Charlemagne in 774 when the King of the Franks conquered all of Lombard northern Italy for the Carolingian Empire.

It was at the itinerant palace school (schola palatina) that Paulinus would stay for about ten years and make the acquaintance of other leading scholars of the age, including Peter of Pisa, Alcuin of York, Fardulf, Arno of Salzburg, Albrico, Riculph, Raefgot, Rado, Lullus, Bassinus, Fuldrad, Eginard, Adalard, and Adelbert.

Paulinus returned from court to his episcopal see and took up residence at Cividale, also the seat of the Carolingian count in charge of the March of Friuli.

In his relations with the churches of Istria, or with the nearby Patriarch of Grado, the representative of Byzantine interests, he exhibited prudence and pastoral zeal.

In 794, he took a leading part in the Frankish national council at Frankfurt, where Adoptionism was again condemned, and composed a book against the heresy which was sent to Spain in the name of the assembled bishops.

[2] Nowadays, the Slovenes regard Paulinus as their apostle who peacefully brought them Christian religion,[3][4] although the true missionary activity in the Aquileian sphere started only after his death.

The patriarch defended the use of the Filioque in the Creed in order to more explicitly contradict Adoptionism,[5] a heresy which taught that Christ was adopted as Son of God when He received the Holy Spirit from the Father at His baptism.

The Adoptionist polemic was based on the assumption that the humanity of Christ did not have the natural ability the send the Holy Spirit, but needed to receive this power by being adopted by the Father.

Walafrid Strabo, a contemporary, noted that the Creed (with the Filioque) "began to be repeated in the liturgy of the Mass more widely and frequently after the deposition of Felix the heretic," one of the prominent Adoptionists.