The reason why science and religion cause conflicts within the person who wants both is simply that they use different methods. Religion, as the root (religare "to bind") implies, is about attaching one's self to a concept and holding on against all different concepts, while science is supposed to be about not attaching your self to any of the concepts, but rather leaving things open to debate. The threat of "science becoming religion" happens, therefore, when people attach themselves to concepts like the Big Bang Theory. And it is true that the pure scientist doubts the Big Bang Theory, because she must doubt everything. But the pop scientist defends theories as if they are facts, and this is how they tie themselves (religare "to bind") to concepts and thwart the real purpose of science.
Note: some say religare means a binding contract between man and God. And I also have it that Cicero gives the root as relegare, to re-read, but I don't buy that.
Anyhow, I try not to tie myself to things. I try to stay unattached, except by choice. With attachment comes a desire to control, and I struggle with that, so I have to make myself not try to control, and the only way to do that is to let things be. As you can see, then, for me, religion is an error, though spiritual thought is a great pleasure. Big different. I guess I should start a threat called "Ask an a-religio-ist anything"! LOL! :)