The Lord Jesus was born in 4 B.C., which was the year Herod the Great died. He was the tyrant who had the children slaughtered in the region of Bethlehem because of what he heard from the wise men, and so obviously, Jesus had to have been born before Herod died.
Dionysus the Insignificant was a Sythian who moved to Rome around 500 A.D. and was the first to propose the change of calendar to mark the years since the Lord’s birth. Given the resources available to him, he did remarkably well, but nevertheless he was still off by four years. What this means is that it has now been 2,008 years since the arrival of the Son of God among us. It has been about 1,975 since He died on the cross and rose again, ascending afterward into Heaven. From the right hand of the Father, He has continuously ruled the world since that glorious time.
Two thousand years into that reign, that 4 year glitch should not trouble us. But if any secularist brings it up as a taunt, we may simply observe that this just means that Jesus has been reigning 4 years longer than we thought.