There are various forms of unity requiring no overcoming of one’s evil inclination, egoism, which do not cause its resistance—egoism does not interfere there. There are also certain kinds of unity supported by egoism, for example, nationalism and fascism.
Therefore, a check on the earthly level is whether we really act for the sake of unity and love without borders. This is the difference.
If you want to do good to your people and your country, and don’t care about the rest of the world, or even on the contrary, if you wish detriment upon other parts of the world, then your entire unity is anti-spiritual. For this reason, it will fail and will be unable to exist. Therefore, Baal HaSulam says that this is a curse on the generations.
From the Conversation in Iceland 5/23/18