"My kingdom is not of this world."
Sound familiar? Christ didn't lift a finger to establish an earthly kingdom WHILE HE WAS ON EARTH.
He doesn't intend that His followers do so now.
So you not only disagree with Leo XIII, you disagree with St. Augustine and 1700 years of Catholic history. Go play with some Protestants - you all will get along just fine.
Sinky: "My kingdom is not of this world."
Just because His Kingdom is not "OF" this world, does not mean, of course, that it is not "IN" this world.
Nice try, Sinky. But Christ definitely established His kingdom (the Church) IN this world. It is just not "OF" this world, because "this world" is Satan's abode.