theories of the universe and the origin of Earth are, unfortunately, often presented as fact by textbooks and teachers. this is a serious problem of basic training. even very generally accepted theories are supposed to remain theories. with respect to the Big Bang, Evolution, Creationism, and others, the problem there is limited time: too many theories and only 35-45 hours in a semester to cover whatever you choose to cover. so we mainly cover the most currently accepted theories that have the most solid evidence. i taught chemistry and biochemistry for 35 years. until recently, we were mainly allowed to steer our own boats, so i taught the currently accepted theories (as theories) but gave some attention to other scientific ideas that have been recently emerging. i think i would be hard pressed to cover any religion-based theories at all since there's no time for it, many students and parents would be strongly against it, my bosses would be against it, and the evidence is very thin compared to the great masses of evidence behind the current scientific theories. to be clear, though, the current theories are not entirely correct, and may be very incorrect in many ways (I'm writing some papers about it right now), but the weight of evidence in favor of them and their emerging descendants will never be even remotely approached by the evidence for Creationism.