How many people are christian and Muslim?

Based on 2010 statistics: Christians outnumber Muslims by about 700,000,000, or a ratio of 1.5 : 1.

Christianity is the world's largest religion by far, with about 2.3 billion followers. Its annual growth rate is 1.3%, or an annual gain of 29,900,000 followers. It is the third fastest growing religion (behind Islam and Hinduism, but not by much truly), but the independent Christian churches and Charismatic Christianity have the highest growth rate of any religion at 2.4%, over half a percent higher than Islam. Christians currently account for about 33% of the world's population (about 1/3).

Islam is the world's second largest religion, with about 1.6 billion followers. Its annual growth rate is 1.8% (half a percent higher than Christianity), and annual gain of 28,800,000. It is the world's fastest growing religion. Muslims currently account for about 23% of the world's population (about 1/4).