[Errant]

Because of the signs in the heavens, the positions of the constellations which can be now be determined to the exact day in history with today's computers.

[null and void]

OK. Fair enough.

I still maintain that the one Biblically fixed date, the one that is explicitly stated, the one that doesn't require a digital orrery to fix, is the Resurrection.

I also believe that this is the defining moment of Christianity, and that the Christian calendar should start on the first Easter morning.

That is, of course if one insists on not using the calendar that was good enough for Jesus himself to use!