If you’re wondering, this is because the dates were not set until several hundred years after Jesus died, and the monk who did it fucked up. They calculated a date and set that as the first year (there is no 0 between 1 BC and 1 AD) almost 500 years after Jesus was born.
Then later they counted again, finding they were off by 4-6 years and they miscalculated, and instead of changing the entire calendar for the whole world, they bumped Jesus’ birthdate instead.
If you’re wondering, this is because the dates were not set until several hundred years after Jesus died, and the monk who did it fucked up. They calculated a date and set that as the first year (there is no 0 between 1 BC and 1 AD) almost 500 years after Jesus was born.
Then later they counted again, finding they were off by 4-6 years and they miscalculated, and instead of changing the entire calendar for the whole world, they bumped Jesus’ birthdate instead.