Jonas is not known for his writings, in fact, he didn’t leave behind many writings. He is known as a faithful teacher of God’s Word, and Luther’s closest friend and colleague. He was a master of Greek, Hebrew and Latin. Jonas, Luther and Philipp Melanchthon where the driving theological force in Wittenberg.
Initially, Jonas was a follower of Erasmus of Rotterdam, the great philosopher. At the start of the Reformation, the two sides were in agreement that the church needed to be reformed. Erasmus was more interested in a gradual reform while Luther was adamant that the focus be centered on the immediate need to preach the Gospel in its purity.
Jonas was won over by Luther’s theology, much to Erasmus’ consternation at having lost such an able disciple. Jonas literally began to follow Luther as the reformer traveled through Erfurt on his way to the Diet of Worms in 1521. He was at Luther’s side when he stood up to the Emperor at Worms. And he was at Luther’s bedside as the reformer took his last breath in 1546.