Although Mark Twain is certainly not the most respected name in Christendom (he made serious fun of the Christian view of Heaven), he is famous. Here is his quote on a Christian’s duty to vote, via Thinking Right.
It will be conceded that a Christian’s first duty is to God. Then follows, as a matter of course, that it is his duty to carry his Christian code of morals to the polls and vote them. Whenever he shall do that, he will not find himself voting for an unclean man, a dishonest man.
If all Christians would vote their duty to God at the polls, they would carry every election, and do it with ease. Their prodigious power would be quickly realized and recognized, and afterward there would be no unclean candidates upon any ticket, and graft would cease.
If the Christians of America could be persuaded to vote God and a clean ticket, it would bring about a moral revolution that would be ever incalculably beneficent. It would save the country.”
(Colliers magazine, September 2, 1904)