Sometime between 1527 and 1529, Dévay became a supporter of the Protestant Reformation, and in 1529, he traveled to the
University of Wittenberg to study under Martin Luther and Philip Melanchthon. As Luther's student, Dévay lived in Luther's house, a common practice in those days. The house and the student rooms are preserved in Wittenberg
.
He returned to Buda by 1531, becoming the
Calvinism. Hungarian Protestants came to distinguish between their faith, which they called magyar hit (Hungarian faith), from what they called német hit (German faith) (i.e. Lutheranism
).
Dévay soon left Buda to become minister at
Bishop of Vienna
, another close adviser of Ferdinand, and a committed opponent of the Reformation. Biro was released soon after his trial, and returned to Buda where he resumed his work as a reformer. In 1532, he was re-arrested, and remained in prison until 1534.
Upon his release from prison, Dévay came under the protection of
Tamás I Nádasdy. Dévay devoted his time to refuting the works of Gregory Szegedy, a doctor of the Sorbonne and provincial superior of the Franciscans in Hungary, who had written in opposition to the Reformation. Dévay wrote Orthographica Hungarica', the first book published in Hungarian
.
In spite of King Ferdinand's opposition to the Reformation, Dévay supported Ferdinand's claim to the throne as opposed to his rival
Helvetic Confession on the topic of the Lord's Supper
.
After returning to Hungary, Dévay was a zealous advocate of the
