On the internet, short of blocking them on social media, you are confronted with them constantly.
Actually, I think it's the ability to block (or just de-friend) that creates the biggest part of the problem. It creates echo chamber effects, which help ideas morph into their most virulent and effective forms, especially ideas that demonize the holders of opposing ideas -- which, from a memetic evolutionary perspective are really cooperating ideas, not competing at all.
A good, though somewhat annoyingly dumbed down, explanation of this process and effect is this youtube video. If you haven't watched it, you really should -- and then think about the ideas that you hold and consider the possibility that they have evolved specifically to push your hot buttons in the most effective way possible, and how you can counter that.