We in religious studies tend to like these terms, AD rather than BC, Before Christ, and AD, because AD actually stands for Anno Domini, in the year of our Lord.
It's very simple, when you go to Acts, when those men who were scared because the Lord and Savior Jesus Christ has been taken away from them, they were told to go to an upper room.
If someone makes a decision to accept Jesus Christ as their Lord and Savior because they were inspired by Ray Lewis exhortation of his faith on Super Bowl Sunday, great.