Hey man, I know how you might feel. As Christians we are meant to be Gods ambassadors but we always do a royal job of screwing up. History is a testament to this, it always teaches us that man makes mistakes and to never put your faith in man. Never follow the mainstream or the crowd either, if you want to find something out, you have to look into the matter yourself. Anyway I think the people in question are only doing what they think is the right thing.

One reason I can think of is that as Americas your culture was heavily intertwined with Christianity. You guys at one point were like the ambassadors of it to the world. Then all of a sudden things changed and things became almost too lawless and too liberal. I think if you studied deep into politics you might understand why some of them think they way they think, however misguided they could be.

To answer your first question, when your brain just doesn't have all the pieces to the puzzle, you need to have faith in the mean time. Keep looking into it. Look at arguments from scientists who do believe in God and see what they have to say. And finally this scripture is true for anybody who wants to find God:

Jeremiah 29:13

"You will seek me and find me when you seek me with all your heart."