People don't "preach" evolution. It's not a philosophy or a way of life. Christians and Jews and Hindus AND atheists all accept the obvious findings of science with regard to the evolution of species.<quoted text>
Unfortunately, people preaching Evolution rarely do observe scientific method.
And it doesn't matter whether people debating on a message board "observe the scientific method," but only that scientists doing research in field and lab observe the method when analyzing and describing evolution -- and they do, as evidenced by the hundreds of thousands of extant peer-reviewed scientific papers and studies on evolution.