Max Weber's classic Protestant Ethic and the Spirit of Capitalism answers this question in a way that I have always found convincing, though it is contested.

Essentially, the puritanical Calvanist sect believed that everyone was either predestined for heaven or damnation and that there was nothing they could do to change that, as being able to change it would make one more powerful than God. This sense of predestination caused a lot of angst amongst these believers as they were tremendously devout and terrified of hell. In order to alleviate this anxiety they sought evidence that they were the 'Elect', that is, those predestined for salvation. It was taught that material wealth and financial success were evidence of one's election and so Calvanists became early capitalists, investing and reinvesting in order to put their minds at ease.

Up until this, work was considered a necessary evil and the Christianity's teachings on wealth and good works are well known. Calvinism, according to Weber, triggered a change in attitude towards the accumulation of wealth that later influenced wider society.

I guess this became the most efficient economic model and non-Protestant societies adopted similar attitudes in order to keep up. This, I am less sure about. I don't remember Weber going in to this but I would be interested in hearing how people think Weber's idea of the origins of capitalism spread beyond Calvanist communities.