Ah but see there is one technically correct answer to that question: casual sex is actually harmless as long as it's consensual and you use protection correctly. The fact that some people do not like that very simple fact does not change it. It's their problem.
And again I caution you (I assume it's the same AC) against concepts like "objective science". Science cannot be objective, it is made by humans for humans. Evolution is not more "scientifically proven" or "objective science" than the fact that consensual protected sex is harmless. You can spend time trying to find a qualitative difference why one is more correct than the other, but you will fail to find a valid one. As it turns out, some people will tell you that believing in evolution is harmful and will result in you going to "hell", whatever that is.