Pew's report on major world religions contains some eye-opening graphics. Among them:
The global reach of Christianity is pretty hard to miss. The entire Western hemisphere is majority Christian, as is virtually all of Europe, much of sub-Saharan Africa, even small parts of Asia. If you lived in one of those green or yellow countries, do you think Christianity would look threatened to you? Asia, of course, is the big exception to Christianity’s otherwise common status as majority religion. But there are huge numbers of Christians even there.