I know that answer may be due to convenience, however I wanted to know if there was something I was missing. I do not know how accurate the 25th of December is for the birth of Jesus, but that is the date that we go by. We stop the BC (before Christ) count after he is born so why not start there?
Because the church adopted the julian (roman) calender. The romans already had a calendar that started in Januarius and ended in December. They took that one and changed the starting date from 753 BC (founding of Rome) to 1 AD. So Jezus was born on the 25th of December of the year 1 if we ignore the discussion about the accuracy of his birthday. Check out the FAQ for some great previous answers on calender and timekeeping questions:
https://www.reddit.com/r/AskHistorians/wiki/calendars