They, are in fact, not contradictory doctrines at all. This was explicitly the subject of Max Webers paper from 1904-5, "The Protestant Ethic and the Spirit of Capitalism".
Forthunately or unfortunately, the best precis I can find come from a critivcal site so excuse the term "supposed" in the following:
quote:
"Weber's most famous book is The Protestant Ethic and the Spirit of Capitalism. It is generally taken as a counter to the Marxist thesis of the primacy of base over superstructure: Weber is supposed to have argued in this book that capitalism in fact developed historically as a result of a religious movement, protestantism, specifically Calvinism. The argument is that Calvinism, with its doctrine of predestination - i.e. the doctrine that God eternally decreed the salvation of some and the damnation of others, not in view of the good or evil deeds they would do, but simply 'because he willed it' - that this doctrine made Calvinists anxious about their salvation; that this led them to seek reassurance in attempting to succeed in their economic (and other) undertakings, in the belief that God signifies his favour by giving prosperity to the undertakings of the elect; at the same time the Calvinist did not spend his money on self-indulgence, so had nothing else to do with it but plough it back into the business. And his employees, being Calvinists also, had a sense of their jobs as 'callings' to be done well out of religious duty even for small earthly reward. Hence the 'Protestant ethic' - the famous 'work ethic' -, the drive for economic success, the will to work hard, the habit of not spending on frivolous self-indulgence - all this, originating in theology, provided a 'spirit' for capitalism, the set of motivations and attitudes that led to 'rational investment' of profits continually ploughed back, and to the modern world."
In other words, wealth indicates the approval of god. The most wealthy are those who are the most holy. As we can see, there is a close correaltion between the geographic presence of Calvinistic ideas and the vehemence with which Capitalist dogma is held. As an initial colony comprised of religious extremists, its not that surprising that the US continues to exhibit Calvinism red in tooth and claw.