He was born at Quedlinburg, where his father was councillor of the consistory. He took the degree of magister artium at Wittenberg in 1729, and became assistant master of the gymnasium there; in 1741 he was appointed conrector of the gymnasium, and a year later he became professor of philosophy and cathedral preacher.
In 1747 he resigned his posts at Wittenberg, and accepted an invitation to Herborn as director of the Pädagogium and head of the Lutheran community. In 1754 he left Herborn to become consistorial councilor of the count of Solms and superintendent at Braunfels. In 1765 he was appointed abbot of Michaelstein, and in 1770 abbot of Mariental.
He died in Quedlinburg.
Cramer's writings include:
* _Poesie der Deutschen_ (1744), an anthology of German poetry
* _Betrachtungen über die Gedichte der Deutschen_ (1744), a commentary on German poetry
* _Kurzer Entwurf einer Unterweisung in der Vernunftlehre und Moralphilosophie_ (1745), a textbook on philosophy
* _Christliche Sittenlehre_ (1746), a textbook on Christian ethics
* _Vernunftlehre_ (1747), a textbook on logic
* _Metaphysik_ (1747), a textbook on metaphysics
* _Anfangsgründe der Metaphysik_ (1750), a simplified version of his textbook on metaphysics
* _Theologia naturalis_ (1754), a textbook on natural theology
* _Sendschreiben an Herrn Christoph Ernst Schubert, über die Natur und Notwendigkeit des natürlichen Erkennbarkeits-Merkmals der geoffenbarten Wahrheit_ (1760), a controversial work on the relationship between natural and revealed religion
* _Systematische Entwurf der evangelisch-reformierten Theologie_ (1762), a systematic treatment of Reformed theology
* _De ratione studiorum academicorum_ (1764), a treatise on the proper method of academic study
* _Vernunftmäßige Beweise von der Wahrheit und Göttlichkeit der Christlichen Religion_ (1765), a defense of the truth and divinity of the Christian religion
* _Unparteiische Betrachtungen über die jetzigen Religionsstreitigkeiten_ (1766), an impartial assessment of the current religious controversies
* _Die Religion der Vernünftigen_ (1767), an exposition of the religion of the reasonable
* _Theologische Untersuchungen_ (1771-1775), a collection of theological essays
* _Lebensbeschreibungen gelehrter und berühmter Männer_ (1774-1775), a biographical dictionary of learned and famous men
* _Geschichte des Lebens Philipp Melanchthons_ (1775), a biography of Philipp Melanchthon
* _Sammlung auserlesener kleiner geistlichen Schriften_ (1780), a collection of selected small religious writings
* _Nachrichten von seinem Leben und Wirken, von ihm selbst aufgesetzt_ (1781), an autobiographical account of his life and work