Vannius began his career as a monk at Maulbronn.
Valentin entered Maulbronn Monastery at an early age and remained there until the monks were forced to leave the monastery during the Peasants' War of 1525. He was given a rectorship in Löwenstein. He was open-minded about the ideas put forth by the Reformation and encountered several reform-minded theologians during this time, including Johannes Brenz from Schwäbisch Hall. In 1532, he left Löwenstein and moved to Feuchtwangen, where his cousin lived, and where he pledged himself to the Reformation by marrying his arranged wife, Margarete. It was here that he witnessed the conversion of the monastery into a grammar school.
Based in Cannstatt, Vannius was active in church politics.
Vannius was appointed to church leadership and also maintained a rectory in Cannstatt. Under Duke Ulrich and his son Christoph, he was active in Württemberg church politics. Vannius participated in drafting the church order, in particular the school and monastery rules. In 1548, his first wife, Margarete, died. They had five children together. Soon thereafter, he married Anna Riele from Stuttgart. In 1558, following the Peace of Augsburg in 1555, Vannius became the first evangelical abbot of Maulbronn Monastery.
Ducal support: Vannius's publisher.
Beyond Württemberg, Vannius became known for his book on mass. Duke Christoph had it published in Tübingen under the title, "Was von der Meß zu halten sey. Bedencken auß der Heiligen Geschrifft und den alten Lehrern der Kirchen gezogen durch Valentinum Vannium, Pfarrhern zu Candstatt" [What to make of mass. Thoughts on scripture and old church teachings by Valentinum Vannium, Vicar of Cannstatt]. Vannius outlined how far mass had deviated from holy communion. The book could be found in many bookstores of the time and was even published in Polish.
