Then the argument is usually "no, your country doesn't exist, you just made it up", same thing they use for Palestine. But you can bring up that Israel didn't exist until people decided it did and made it up. Then they'll talk about it being recognized. You can bring up numerous countries that are recognized by some, not others, and eventually the argument becomes "No, it only counts when I, the liberal currently speaking, decide that it counts as a country with a right to exist".
Then the argument is usually "no, your country doesn't exist, you just made it up", same thing they use for Palestine. But you can bring up that Israel didn't exist until people decided it did and made it up. Then they'll talk about it being recognized. You can bring up numerous countries that are recognized by some, not others, and eventually the argument becomes "No, it only counts when I, the liberal currently speaking, decide that it counts as a country with a right to exist".