It's not about vocabulary. It's about understanding scientific jargon - and I don't expect non-scientists to understand all the jargon.

People can disagree all they want, as long as they don't disagree on the basis of "just a theory". Because evolution isn't just a theory... a century of comparative anatomy and several decades of genetic science and the entire foundation of biology make it fact. I'd rather people debate the "cause" of evolution than its factual basis, which isn't really up for debate even a tiny bit.