Hmmm, this poem definitely is open to a lot of interpretation. "When it comes?" is the underlining question that you present.
But what is "it"?
Maybe the Second Coming is what "it" is?
And the importance of all this coming together is becoming Christians, or at least following some kind of religion. Or just working together as a large, good community to make this world a better place.

Whatever the interpretation, it was a interesting and good poem.