Haven't a clue. Found this:
The terms Old Lights and New Lights (among others) are used in Christian circles to distinguish between two groups who were initially the same, but have come to a disagreement. These terms have been applied in a wide variety of ways, and the meaning must be determined from context. Typically, if a denomination is changing, and some refuse to change, and the denomination splits, those who did not change are referred to as the "Old Lights", and the ones who changed are referred to as the "New Lights".
[link to en.wikipedia.org]

but if they did a split, it's news to me.

Edited to add: "Haven't a clue", was referring to the new light, not Nostradamus."