Twilight Hue
Twilight, not bright nor dark, good nor bad.
That kind of explains the Christian origin. It was the almost mid 1600's. I suppose not being a Christian in that era would be rather difficult.I would not say that it was a "couple". For example one of the first laws of geology was written by a Christian, who was also a creationist. The law of superposition:
The oldest stuff is on the bottom
Nicolas Steno was the first to realize what seems obvious today. That the lower level sedimentary rocks had to be older than those on top. He never got to the point where he doubted the Flood, but he laid some very important groundwork for it:
Nicolas Steno - Wikipedia