Probably joined the Moravian Church in Herrnhaag, Hesse, Germany. In 1796 came to the Moravian settlement at Bethlehem, Northampton Co., PA. Taught at the Boys' School at Bethlehem. Ordained 16 Apr 1803. Married by Lot, first wife proposed by Elders was Salome DEHUF, then Maria CHRIST, then finally Hannah FEARNLEY. Married 28 Apr same year. First charge Oldman's Creek, Gloucester Co., NJ.
"Sketch of the History of the Moravian Congregation at Gnadenhu"tten on the Mahoning," by Robert Rau.
Night of 24 Nov 1755, 10 of 16 Moravians killed. Settlement started again 1770.
"John Caspar Freytag and Hannah (m.n. FEARNLEY) his wife were sent to minister to the remnant of this congregation in November of 1805. A comparatively young man, of bouyant spirits and vigorous health, he entered upon his duties as minister, school-teacher, and husbandman, with zeal and ardor."
Last of the Gnadenutten congregation were preparing to leave for Ohio in 1813. Retired, bought farm Cherryville, died five years later.

• Married: 28 Apr 1803 in Central Moravian Church, Bethlehem, Northampton Co., PA
• Note: These two met in the Moravian settlement congregation at Bethlehem, Northampton Co., PA. Married by the Rev. George Heinrich LOSKIEL.

1. Catharine FREITAG b: 1 Sep 1805 in Bethlehem, Northampton Co., PA
2. Maria FREITAG b: 2 Apr 1807 in Gnadenhuetten Moravian Church on the Mahoning, Penn Tp., Northampton now Carbon Co. PA c: 19 Apr 1807 in Gnadenhuetten Moravian Church on the Mahoning, Penn Tp., Northampton now Carbon Co. PA
3. Justina Birkby FREITAG b: 12 Oct 1810 in Gnadenhuetten Moravian Church on the Mahoning, Penn Tp., Northampton now Carbon Co. PA c: 18 Nov 1810 in Gnadenhuetten Moravian Church on the Mahoning, Penn Tp., Northampton now Carbon Co. PA
4. John Augustus FREITAG b: 20 Aug 1812 c: 9 Sep 1812 in Gnadenhuetten Moravian Church on the Mahoning, Penn Tp., Northampton now Carbon Co. PA