To get some perspective on the growth/decline of world religions, here are some numbers. There are 2.2 billion Christians in the world, and 1.1 billion Catholics (1 billion other Christian denominations).

While Catholicism is declining steadily, especially in Western countries, the number of American Catholics is steady because of the large immigrant (especially Mexicans) population. America is No. 3 in the world-ranking for the most Catholics, after Brazil and the Philippines.

Here is a summary of religions in America (Source Adherents.com):

The number of Muslims in the world continues to grow through strong financial support and proselytizing, especially in Mid-East countries. Islam has now overtaken Catholicism as the world's largest religion.

• Largest Religious Groups in the USA
• Major Religions of the World Ranked by Number of Adherents
• Religions are a divisive force in the world