Peter Lorenz Sellergren was born in Jönköping in 1768 to gunsmith Petter Sellegren and Anna Maria Björkander.

"[2] After his faith began to falter in contact with Enlightenment literature, he indulged in alcohol abuse to the point that he was called to the cathedral chapter in 1813 and forced to take a leave of absence.

Physically as well as mentally weak, he experienced a remarkable religious breakthrough during that time and was able to continue his priestly ministry thereafter.

[5] His preaching was of an Old Pietistic nature, but in time, partly through the influence of Johann Arndt and Johan Möller, bishop of Visby, it acquired a stronger evangelical element.

[6] He made an impression on the Palmqvist family, several of whom (Per, Gustaf, and Johannes) would later become pioneers in the early Swedish Baptist movement in Sweden and the United States.