All nations in the future will see that Hashem spoke:^[1]

It states in scripture that in the future G-d will turn to all the nations to speak to them in one language. This means that all of mankind will serve G-d in unison. This will result from a great revelation of the speech of G-d which is a revelation of the G-dliness of the attribute of Chochmah.

[1] Torah Or 12a