Troll him, preferably with a surprising but falsely reassuring response like ‘Good point. You really showed me how wrong I was. I wish that I were as smart as you.’

Convincing anticommies to research anything that contradicts their meme ideology is like pulling teeth, so I usually don’t bother. It’s better to continue advancing your own education or talking with novice socialists to advance theirs. Devout antisocialists can wallow in their cluelessness for all I care.