Before revision: Sociologist Phil Zuckerman's global studies on atheism have indicated that global atheism may be in decline due to irreligious countries having the lowest birth rates in the world and religious countries having higher birth rates in general .Zuckerman, Phil (2006).
After revision: Sociologist Phil Zuckerman's global studies on atheism have indicated that global atheism may be in decline , but that it is hard to predict future trends due rapid secularisation in rich countries existing alongside higher birth rates in religious countries .Zuckerman, Phil (2006).