Christianity today, practiced by over 2 billion followers, is undoubtedly the world's largest religion. But of course, it hasn't always been this way. It began in the city of Rome, around the time of the Emperor Claudius who reigned from 41 to 54 CE. It is believed to have originated in the Roman province of Judea . Geography usually plays a big role in determining the success of developing cultures. According to Michael Gough, who wrote The Early Christians, this was the case for Christianity because the "geography [...] determined the direction and rate of spread of the new religion." However, with a good geography comes great diversity as well. For instance, at the time, the three most influential religions of the orient were the pagan ones known as Cybele, Isis, and Mithraism. L.P. Wilkinson, in his book The Roman Experience, discusses how Mithraism had parallels to Christianity in the sense that...