How I can be a "liberal" and still be Christian?

I've heard a lot of Evangelicals talk about how we in this relativist, post-modern world shouldn't "pick and choose" which part of the Bible we believe in. Usually they do this because they think that Romans 1 makes it okay to hate homosexuals or that Genesis 2 should be taught in public schools.

But it seems to me sometimes that Republican Christians believe in Matthew 28, but choose to ignore Matthew 25. Helping the poor and upholding justice for aliens and widows shows up far more often than almost anything else in the Bible.