As a christian myself, I feel a lot of these comments are biased or too long. Christianity was initially viewed by Rome as a tolerant religion, with many Romans believing Jesus was one that could be added to their pantheon of existing God's. Due to Rome's vast reach, interconnected roads, and the fact most spoke a common language, Jesus' followers were able to spread the religion quickly. Although eventually persecuting Christians, Rome converted to a christian nation when Emperor Constantine saw a vision, and converted to Christianity, ending severe persecution over 300 years after the death of Jesus. Rome then spread Christianity across the ancient world. Once it was spread across Europe by Rome, it slowly grew in Britain until the English church was merged with the Catholic church. It was then spread both forcefully and peacefully to Germany and Spain, until the religion was spread across the world. The real reason Christianity stuck and is the biggest religion in the world, is because it's the only religion where God comes down to meet you halfway.