Darwin himself was careful to tiptoe around the implications of his theory. He wanted to spend his time thinking about biology, not arguing with people who accused him of being an atheist.
The trouble with keeping your thoughts secret, though, is that
you lose the advantages of discussion. Talking about an idea leads
to more ideas. So the optimal plan, if you can manage it, is to
have a few trusted friends you can speak openly to.
In my blog post, “Subtle Mid-Stage Startup Pitfalls” I said:
You can’t prevent yourself from being a target. It’s an automatic
consequence of being successful. So the best you can do is react
in the right way when people attack you. To some extent you have
to resign yourself to letting people lie about you.