Zwingli received a thorough classical education in Basel, Bern, and Vienna, and was considerably influenced by the humanist precepts of Erasmus. His devotion to learning and his passion for individual freedom, developed through contact with the self-governing Swiss cantons, were important influences in his life. In 1506 he was ordained and appointed pastor of Glarus; he also served (1513, 1515) as chaplain to Swiss mercenaries in Italy. In 1516 he became people's vicar at Einsiedeln. While there Zwingli began to formulate the ideas that were to lead him to renounce the church of Rome.
Unlike Martin Luther, Zwingli experienced no acute religious crisis—he became a reformer through his studies. Later he was to adopt Luther's doctrine of justification by faith alone, but Zwingli's independent study of Scriptures had already led him to question the teaching of the Roman Catholic Church. When he became vicar at the Grossmünster of Zürich in 1518 he found the democratic institutions of the community amenable to his beliefs. In 1519 he successfully opposed the dispensing of indulgences in the city and soon was preaching against clerical celibacy, monasticism, and many other church practices.