If AD marks the year of his conception, then it isn't 2013AD, but somewhere between 2017 - 2025AD since evidence suggests that if such a person as Jesus was born, he was born somewhere between 12 - 4BC with a time of year closer to summer than early winter.
Where do you get conception? Where? AD = After Death.
Yes, BC = Before Christ, thus before he was born. (side note, conception also is not the same as being born).
Yes, this does mean there missing years. Jesus Christ was 33 years old when he died on the cross. Not 17-25 years old....plus 9 months. No, the western calendar does not reflect this. Why? Because it's the Catholic church, they don't pay attention to reason. (Can you spot the atheist here, kids? If you guessed me, you were right! Yay!)
http://en.wikipedia.org/wiki/Anno_Domini
pretty sure we've been regularily using BCE and CE(before common era/ common era) for a decade or so now.
