It was during this time that we have record of Calvin’s first ventures in to preaching. In addition to studying Law and Greek and lecturing on rhetoric at the Augustinian convent where Augustin Marlorat, a future Reformer, was prior, Calvin began preaching in their church and in the surrounding villages. In one village, the local squire was taken with his preaching even though he was not immediately converted as a result.
This behavior is certainly significant. While he might have preached as a Roman Catholic or a humanist, there would have been little motivation for him to do so. Many students of Calvin place his conversion shortly before this time (in 1529 or 1530) and since a desire to bear witness to the faith is one of the marks of the evangelical Christian, his preaching would certainly seem to bear witness to this.
Calvin was also studying the Eucharistic controversy during this period. Luther had published his Babylonian Captivity of the Church in 1520 in which he rejected the Mass as a sacrifice and interpreted it instead as a sacrament of God’s promise and the gift of Christ received only by faith. Calvin read this and two of Luther’s sermons on the Eucharist that had been translated into Latin.
The other book that one may be certain Calvin was reading during this time was Erasmus’ Greek New Testament. The 1527 edition had the Greek text and Erasmus’ Latin translation in facing columns. Parker theorizes that Calvin may have been frustrated at his lack of Hebrew which made him depend on the Vulgate to read the Old Testament.
Calvin’s father passed away during Calvin’s stay in Bourges and a short time thereafter, Calvin published his first book, a commentary on Seneca. For reasons unknown, Calvin then returned to Orleans and later to Paris.
It was during this stay in Paris that Calvin found himself at the center of some rather stirring events. On All Saint’s Day in 1533, his friend Nicholas Cop was to deliver an address at the opening day of the winter term at the University of Paris. Expecting a sermon in the usual Roman Catholic style and replete with the usual Roman dogma, the Sorbonne was furious when Cop chose the Beatitudes (Matthew 5:2-12) as his text and “[…] incorporated in his message some of the teaching of Erasmus and Luther, whose writings were hated by the Sorbonne. Then he upheld the Bible as the living Word of God, and he talked of God’s free mercy to sinners.”
Many today still suppose that Calvin wrote this address, a fact which cannot be proved or disproved. One thing is clear, Calvin was implicated in Cop’s address and as a result his room was searched, his papers and books confiscated, and he himself was forced to flee the city as Cop had done. Now Calvin had crossed the line and was not only firmly entrenched in the Reformation, but firmly associated with it as well.
Calvin’s next few years were spent in and out of hiding until he finally settled in Basel, located in what is now Switzerland, in January 1535 and began working on two projects. The first was assisting his friend Pierre Robert on a French Translation of the Bible. After its first publication, Robert left Basel but asked Calvin to edit the New Testament for the second edition. In September of that year he wrote to their mutual friend Libertet and informed him that from there on out he would “[…] set apart an hour every day to be bestowed on this work.”
Undoubtedly, though, the main focus of Calvin’s energy during this period was the first edition of his Christianae Religionus Institutio (Institutes of the Christian Religion) which was published a few months later in March, 1536. Calvin then quietly left the city for Italy before returning to France. The king of France had issued the Edict of Lyon which allowed French “heretics” six month’s grace to consider their ways before returning to the Catholic fold. Calvin used less than half of his six months’ grace and, with his brother Antoine, their half-sister Marie, and several residents of their hometown of Noyon, departed for Strasbourg where he planned to settle down in peace and pursue his literary aspirations. But God had other plans for him.
 Parker, John Calvin: A Biography, 21-22.
 E. M. Johnson, Man of Geneva, the Story of John Calvin (Edinburgh: Banner of Truth, 1977), 31.
 The Letters of John Calvin, (Edinburgh: Banner of Truth, 1980), 34.