When Misapplied Christianity Makes Me Want To Be Violent

I love people.

Let me be clear about this up front. I love people, but I hate some of the stupid things people do. Especially in the name of Christianity.

Let me give you a real quick recap: the Crusades, the Inquisition, etc. And sometimes it's not what they do as much as what they neglect to oppose: Nazi Germany, McCarthyism, racism, sexism.

And then there are the attitudes that really make my blood boil. Let me first make a point about the Christ I know.
Jesus was called a friend of sinners. He was accused (rightfully) of eating with sinners and tax collecters. He regularly criticized the self-righteous religious leaders of his day for knowing, expanding, and perpetrating an Unlivable Law onto others when they couldn't truly live it themselves.
He pardoned prostitutes, admonishing them to end their immoral behavior. He challenged the pious-but-wealthy to see the needs of others as more important than their status or comfort. He welcomed the most reviled characters and the lowest of the blue-collar workers and the most foolish and foolhardy into his inner circle. He fed the hungry, welcomed the children, spoke with the outcasts, touched the lepers, and raised the dead to postpone people's grief.
In short, no one has ever been more powerfully kind, generous, forgiving, or merciful.
And then, there's the story of Jesus entering the temple court and driving out the money-changers, the con-artists, and the price-gouging opportunists. What made Him so angry, I believe--at least in part--was the total lack of respect for the character of God. Yes, God is righteous, God is just, and God is holy. But we must also realize that God is merciful, compassionate, and doesn't want anyone to die without Him. We are His most prized creation.

And people, in the name of Christ, continue to forget what He stood for. Jesus hated sin in all forms, but He loved people no matter who they were or where they came from or what they had done. I don't know them, and I'm sure their intentions are good, but everytime I walk through the streets of my city in our downtown area at night I see a small group of people who consistently trample not just what I believe, but filet the work people like me put into building relationships with the Church's castaways--the disenfranchised.
"God Hates Sin" their signs say, forgetting to say that God still loves the sinners.
"Homosexuality is wrong, and homosexuals are hell-bound" their placards proclaim, denying that the Holy Spirit draws all people to Himself.
"A moment of pleasure, an eternity of torment" their posters postulate, ignoring that though our choices have consequences, God is also a God of grace.

My heart bleeds, my blood boils, and my mind rages. My greatest desire is to walk up to them, confront their heartless, hateful, sadistic form of "Christianity," and rip their signs into small enough pieces to shove them up their ... anyway, it makes me really mad.
Why do I not take a stand? I have only excuses, not reasons: they won't listen, they won't change, I could possibly be arrested for assault, I might embarrass my friends or family, or they won't understand enough to realize the WHY of my actions. So, my blog-friends, please advise me how I can change so I can show them how to change.