>> The year 1 A.D. ended one year after the birth of Christ.
When did it begin?
See #44.
That is a problem, isn’t it?
As far as I know, theoretically, the year Christ was born was AD 1 (the year of our Lord 1, or the first year of our Lord).
The year before that was 1 BC.
But since He was probably born between 4 and 6 BC, this whole argument is really very silly (except in the case of the ordinal numbering of centuries, an entirely artificial construct anyway).