Christianity has had 2000 years to promote democracy.
Judaism has had 5000 years to promote democracy.
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What's your point?
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Religion is not in the business of promoting any kind of government based on reason, and never has been.
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The development of western democracy - government based on reason in which public policy choices are made by the broad base of an informed electorate - was about replacing the divine right of kings.
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That's the whole idea.