Claim. The profusion of mutually-unintelligible human languages is a consequence of the Fall — symbolized by the Tower of Babel — and the principle of restoration through indemnity requires the unification of all languages around one mother tongue at the Second Advent; that language must be the language of Christ at the Second Advent and the True Parents, which is Korean.
Elaboration. Per dp-5-the-chaotic-profusion-of-languages-and-the-necessity-for-their-unification: had humanity not fallen, we “would have formed one global family… likened to a body whose members are all interlinked with God as their head,” sharing one language. The vertical God-relationship severed at the Fall cut the horizontal between-people relationships — humanity splintered, dispersed, and formed isolated linguistic communities.
Babel as Fall consequence. Noah’s descendants shared a common language. Then “the descendants of Noah’s second son Ham, who had sinned against God, built the Tower of Babel… thus furthering the will of Satan. When the descendants of Shem and Japheth, who stood on God’s side, helped with the construction, God brought such confusion to their languages that they could no longer communicate.” Babel-confusion is a protective providential measure against Satan’s-side cooperation, not arbitrary punishment.
Restoration requires unification. As offspring of the same parents, all humans share joy, anger, sorrow, pleasure — yet cannot share deepest feelings across language barriers. Realizing the ideal world of one global family honoring Christ at the Second Advent as True Parent requires linguistic unification. Babel-chaos arose from glorifying Satan’s will; the indemnity-correlate requires participation “in the construction of God’s tower and the glorification of God’s Will as the way to unify all languages.”
Korean as providential language. “Based upon which language will all languages be unified? The answer is obvious. Children should learn the language of their parents. If Christ does indeed return to the land of Korea, then he will certainly use the Korean language, which will then become the mother tongue for all humanity. Eventually, all people should speak the True Parents’ language as their mother tongue. All of humanity will become one people and use one language, thus establishing one global nation under God.”
The argument-form is parent-child filial-piety, not linguistic merit: it is because Christ’s earthly language is Korean (per §3’s Korea-as-SA-nation derivation) that Korean becomes the global mother-tongue.
See also. dp-second-advent-nation-is-in-the-east-and-must-be-korea · dp-cultural-spheres-converge-toward-one-christian-sphere · dp-noah