He was notable as a theologian, sometimes dissenting strongly with his fellow Lutherans, and as a scholar for his editorial work on the Magdeburg Centuries.

Bible Translators Theologians Flacius was born in Labin (Albona) in Istria, son of Andrea Vlacich (Andrija Vlačić[a]) alias Francovich and Jacobea (Jakovica) Luciani, daughter of a wealthy and powerful Albonian civic family.

[9] At the age of sixteen, Flacius went to study in Venice, where he was taught by the humanist Giambattista Cipelli (Baptista Aegnatius / Battista Egnazio).

His intention, however, was diverted by his uncle-in-law,[b] Baldo Lupetina, provincial of the Franciscans and sympathetic to the Reformation cause, who convinced him to start a university career.

[10] Flacius continued his studies in Basel in 1539, then went to Tübingen and finally ended up in Wittenberg, where in (1541) he was welcomed[clarification needed] by Philip Melanchthon.

On 7 May 1557, he was appointed professor of New Testament at the theological faculty in Jena but was soon involved in controversy with his colleague Victorinus Strigel on the synergistic question (relating to the function of the will in the conversion).

[10] Holding to a strong view of what Calvinists later called total depravity, Flacius insisted that human nature was entirely transformed by original sin, human beings were transformed from goodness and almost wholly corrupted with evil, making them kin to the Devil in his view, so that within them, without divine assistance, there lies no power even to cooperate with the Gospel when they hear it preached.

The prioress Catharina von Meerfeld of the Convent of White Ladies [de] secretly harboured him and his family in Frankfurt where he fell ill and died on 11 March 1575.