Max Weber explored the relationship between religion and Capitalism rather thoroughly, and even after all these years, his thesis has never been seriously challenged.

McGrath, et. al. are right that Capitalism has only been around for a few centuries. Max Weber argues very cogently that the rise of protestantism, especially Calvanism, set the stage for the development of capitalism.

The entire essay is available on-line.

The Protestant Ethic and the Spirit of Capitalism