The terms originated in the early 18th century from a split in theological approach among Calvinist denominations concerning the nature of conversion and salvation.
The terms were first used during the First Great Awakening (1730s–40s), which expanded through the British North American colonies in the middle of the 18th century.
[1] In A Faithful Narrative of the Surprising Work of God (1737), Jonathan Edwards, a leader in the Awakening, describes his congregants' vivid experiences with grace as causing a "new light" in their perspective on sin and atonement.
When told of this development, Whitefield famously quipped that he was glad to hear about the fervent faith of his followers but regretted that "so many of his chickens had become ducks.
The "Old Light" Reformed Presbyterians, in keeping with their Covenanter heritage, refused to swear allegiance to the Constitution and thus to become US citizens because the Constitution makes no mention of the Lordship of Christ, and the "New Light" Reformed Presbyterians allowed the swearing.