From this article in the Economist:

Do you believe in God? If you are European, you probably shuffle your feet, look mildly embarrassed, and mutter, “Well, it depends on what you mean by God.” Or something of the sort. In Western Europe, a mere 20% of people go regularly to a service; in Eastern Europe, only 14%. But if you are American, the answer is almost certainly an unabashed “Yes”. Only about 2% of Americans are atheists, and a startling 47% tell pollsters that they go to a religious service at least once a week. Even if that is an over-statement, the broad difference between continents is clear.

To most Europeans, it has seemed obvious for the past century and more that modernism is the foe of religion, and of Christianity in particular. But religion is flourishing in both the developing world and America. The reason is largely the powerful evangelism of new denominations that sprang up in America in the 19th and early 20th centuries.