Gerhardt was the son of Christian Gerhardt, Burgermeister of Grafenhaynichen, near Wittenberg. He enrolled at the University of Wittenberg in 1628. In 1655, he married Anna Maria Barthold. He appears to have frequently preached in Berlin in the 1640’s.

In 1651, Gerhardt was appointed, at the recommendation of the Berlin clergy, Lutheran Probst (chief pastor) at Mittenwalde, near Berlin. In 1657, Gerhardt returned to Berlin as third diaconus of St. Nicholas’ church. However, Gerhardt became involved in the contest between Elector Friedrich Wilhelm (who was of the Reformed Church) and the Lutheran clergy of Berlin; Gerhard was deposed from his office in February 1666, though he still remained in Berlin. In November 1668, he accepted the post of archidiaconus at Lübben an der Spree, was installed in June, 1669, and remained there till his death. The motto on his portrait at Lübben read “Theologus in cribro Satanae versatus.”