You know, I have probably read a good many hundreds of books on American history, and I see very little of this in our history. Although there has been a good bit of pious posturing in that direction.
Even stretching your definitions, few leaders would fit. Washington perhaps, who apparently had a geniune aversion to public life and served out of a sense of duty. With that exception, every leader I can think of was serving at least partly out of personal ambition. This is true because without that ambition driving them they never make it to a position of power.
Your interesting theory also directly contradicts the Constitution and the Federalist Papers, which make it clear that the true foundation of American governance is the expectation that most men act out of their own self-interest, so we design a government system that works because they do.
I don't believe that because men become Christian that power no longer has a corrupting influence on them. The past 1700 years of Christians in political power backs me up on this pretty thoroughly.