My own experience might shed some light on this.
To make a long story short: I was raised in an incredibly Republican and Christian household. No drinking, no smoking, no porn. Went to church every Sunday. Fox News was the only news we could watch. Republican talk radio was the only news we could listen to. Glenn Beck, Hannity, and Rush Limbaugh told us every day how evil and lazy Democrats and liberal-minded people were. Illegal immigrants were to blame for every labor issue. Liberals were to blame for every government issue. Gays were all sick, mentally impaired deviants who just needed to repent from their lifestyles. My father once warned us that America would fall if Obama got elected.
After high school I enlisted in the military. Same kinda deal there too. Fox News on every TV in every waiting room. We watched videos of "insurgents" getting slaughtered on A-10 Warthog flight cams to the music "Let the Bodies hit the floor" before every commander's call. Let's just say Patriotism has never been lacking in my life.
And then, after I left the service, I went to one of the most liberal colleges in the US. CU Boulder. My father warned me not to let those "goddamn" liberal bastards brainwash me. And so I made an effort to remain stalwart against any attack.
A funny thing happened in college. For the first time in my life I was exposed to the other side of the story. Sure, everyone has their agenda, but amazing how your opinion can change on things when you meet the people most affected by them.
Illegal immigrants risked their lives to secure better lives for themselves. Mexico was one of the most violent places in the world and I'd sure as hell do whatever I could to get the hell out. They can earn in a day here what it'd take a month to earn there. Immigrants don't want to destroy our nation, they want a better life for their families. I'd want the same thing if I were in their shoes.
Gays were suddenly people, and not a mental illness. Imagine growing up and feeling the same attraction to the same sex as you feel with the opposite of yours. Now imagine your parents disowning you and/or beating you for having the audacity to be honest with them. You ever wonder why suicide/drug use/sexual promiscuity is such an issue in their community? Treat a person like shit long enough and they'll believe it. They don't want to end the church, they just want the love that some ancient person promised them, and yet all they receive is condemnation and hatred.
I don't hate the US and neither do any Liberal friends I know. We love our country so much we are willing to point out every issue we see as to fix it. Not just ours though, other peoples'. Republicans get a bad rap because they turn a blind eye to every issue that doesn't directly affect them. They harm people they've never met and have no qualms with it.
I still go to church every Sunday. I have a cross on one arm, a flag on the other. You will not meet a more fierce patriot than I. I don't hate our nation. I mourn for what it's become and stand every day to make sure it's better for not just my kids, but everyone's kids.
I feel that if you were given the same experiences I had, you'd feel the same way. We're all worth fighting for.