Was AD started at Christ's birth?

Answer 1

No. The AD system was INVENTED in 525 by Dionysius Exiguus, though it wasn't much used before the 8th century. Nobody is quite sure what Dionysius based his calculations on, but he was trying to date the Christian Era from the Birth (or possibly the conception) of Christ. What is certain is that he got it wrong. Jesus was born at some date between 12 and 4 BC. Fopr more detail, see http://en.wikipedia.org/wiki/Anno_Domini.

Answer 2

No. The common belief that Jesus was born on the year 1 is the result of an innocent mistake made in 533 by the Roman abbot Dionysus Exiguus. He knew that it was impossible to say when Jesus was born, but he knew, or thought he knew, when Herod died. So, he devised the new Christian calendar to begin on the year of Herod's death.

He based the date of Herod's death on the reign of the Roman emperor Augustus, but was unaware that Augustus only adopted that name four years after his reign began, going by his birth name of Octavius until then. So, Exiguus commenced his calendar just 4 years later than he really intended.Even then, it would be an improbable coincidence for Jesus to be born on exactly the same year as Herod died. So, we can only say that the first year AD was later than Christ's birth.