Religion has always been a way to exercise one's own beliefs, not to impress them on others. The main thing that causes people to preach is the fact that they are so blinded by their own faith that they fail to recognize that their faith isn't the only belief. When I visited the campus of Ohio State University, there was a religious protest group going on and on about how we should love Jesus, or hw only he could bring us answers, or some kind of gibberish to that effect. How offended would a non-Christian be walking across campus and having to listen to that? Another reason is that people will sometimes look to religion as a way out. They think that if you pray, everything will be all right. People who can't take responsibility for their own actions can place the blame on God. The last reason is that people throughout history (and some today) would use their religion to their own ends, rather than what it was intended for. Despite vows made, priests have taken bribes, consulted in politics, and committed just about every crime imaginable.
	Religion can also be a tool of destruction. First, more wars have been started over religion than anything else in history. The biggest example is the Crusades, which saw a mass exodus from Europe out into the world to convert the Muslims by order of the Pope. It didn't quite work out the way he planned. Needless loss of life for a difference of opinion. Second, the fact that today, here in this country, we have "in God we trust" on our dollar bills, as well as in many of our songs. And the Pledge of Allegiance doesn't exactly help promote freedom of religion or the First Amendment. Let's say there is a trial, and a witness is called to the stand. He is sworn in on a Bible. Whit if he's not a Christian, or an atheist? Will he be inclined to tell the truth since he can't swear to a god he doesn't believe in? Third, people can use religion to discriminate. It doesn't always have to be illegal like an employer discriminating against a belief. I've seen Christians who have never gone to church, or read the Bible, criticize others for not believing in God. 
