Actually christianity is increasing only in nonwhite developing countries, because of poverty. Everywhere else in wealthier countries, people are turning away from christianity and towards hinduism and other spiritual practices. Even in the west, christianity is associated with poverty and low education. The red-necks and klu-klux-klans (white supremist groups that attack non-whites) are predominantly rural, very poorly educated, and fanatical christians. See the connection?
