Vanderhoven7,
Though I am Jewish, you might be interested to know that outside of the official Jewish-Catholic dialogue sessions, the Parousia was once discussed.
Outside of a few scattered Evanglical Fundamentalist movements and end-of-the-world groups like Jehovah's Witnesses, Christianity at large does NOT teach that the Parousia will occur during human history, but only after it culminates. This allows for the end of the physical universe as foreseen by some current scientific cosmological models.
The Parousia occurs only after history has ended, according to mainstream Protestant, Roman Catholic, and especially Orthodox eschatology. It may occur concurrent with history's end, but will not occur as an element of or during history. The Parousia is an element of eternity and not time according to Christology. Time ends with the beginning of Christ's Parousia.
The Scriptural references to the "nations" knowing about the Messiah's Parousia are not meant to be read as "nations" but as "goyim," or Gentiles. It is using old Jewish idiom about earthly Messianic expectations of the Second Temple era when the Jews believed the Gentiles would recognize their earthly Messiah's arrival (Parousia).
Thus the Church reads this language as allegorical. Jesus never literally "comes" a second time anywhere, at any time. Every Christian will experience death. One day, says mainstream Christianity, the world will literally just stop. But when history ends, according to Christianity a new era begins under Christ. This is the Parousia, and this is what Christianity has understood for 2000 years.
The literal "return" of Christ is an Adventist invention of the American Great Disappointment of 1844 from Baptist preacher William Miller. Witnesses are the result of a group fascinated by the formulas of those days, believing they could still work somehow, and that the group that got the date right was favored by Heaven.
But there's never been such a doctrine of a literal return that would literally be witnessed by the nations, not from Christendom anyway.
You're still buying Miller's snake oil. At least buy the real stuff instead of the knockoff, generic fool's gold.