From The Party Is Over: How Republicans Went Crazy, Democrats Became Useless and the Middle Class Got Shafted by Mike Lofgren (former Republican Congressional staff member):

“Having observed politics up close and personal for most of my adult lifetime, I have come to the conclusion that the rise of politicized religious fundamentalism may have been the key ingredient in the transformation of the Republican Party. Politicized religion provides a substrate of beliefs that rationalizes—at least in the minds of its followers—all three of the GOP’s main tenets: wealth worship, war worship, and the permanent culture war.”

http://www.salon.com/2012/08/05/republicans_slouching_toward_theocracy/

It’s clear that the Democrats are often ineffective, but I‘d argue that they aren’t useless if they sometimes stop the Republicans from doing crazy things. 

In similar fashion, Avram Burg (former speaker of the Israeli parliament) argues that religious fundamentalism is destroying Israel’s democracy:

“The winds of isolation and narrowness are blowing through Israel. Rude and arrogant power brokers, some of whom hold senior positions in government, exclude non-Jews from Israeli public spaces. Graffiti in the streets demonstrates their hidden dreams: a pure Israel with ‘no Arabs’ and ‘no gentiles’. They do not notice what their exclusionary ideas are doing to Israel, to Judaism and to Jews in the diaspora. In the absence of a binding constitution, Israel has no real protection for its minorities or for their freedom of worship and expression.

If this trend continues, all vestiges of democracy will one day disappear, and Israel will become just another Middle Eastern theocracy. It will not be possible to define Israel as a democracy when a Jewish minority rules over a Palestinian majority between the Jordan River and the Mediterranean Sea — controlling millions of people without political rights or basic legal standing.”

http://www.nytimes.com/2012/08/05/opinion/sunday/israels-fading-democracy.html?pagewanted=2&ref=opinion