End,
You have so much to learn my dear brother. I'm doing my best to help you but in the end, you are going to have to put the work and time in yourself.
I never said Christ's first century parousia return was invisible. Indeed He was seen by all. "The whole world" is not the correct translation. Look at Young's Literal Translation (YLT):
Lo, he doth come with the clouds, and see him shall every eye, even those who did pierce him, and wail because of him shall all the tribes of the land. Yes! Amen!
The "tribes of the land" were the Tribes of Israel. They all saw Christ light up the night sky in 66 AD, including those who pierced Him EXACTLY as the passage reads!! Josephus records this event in War 5-6-3:
on the eighth day of the month Xanthicus, [Nisan,] and at the ninth hour of the night, so great a light shone round the altar and the holy house, that it appeared to be bright day time; which lasted for half an hour.
In Rev 8:1 John records that heaven was silent for this same half hour just prior to all heck breaking loose on Jerusalem. Later in Rev 18:1 after the fall of Babylon the Harlot (Jerusalem in 70 AD), John records that an angel having great authority returns. I believe this is Christ's presence returning and again lighting up the sky:
And after these things I saw another messenger coming down out of the heaven, having great authority, and the earth was lightened from his glory.
I look at all scripture and I am happy to explain any that you misunderstand. Go ahead, test me.
I have been there too, twice, most recently in 2015. This valley is not where the battle called "Armageddon" takes place. This is the location of where the foreign troops gathered. Read the passage closely. Here it is in YLT.
for they are spirits of demons, doing signs -- which go forth unto the kings of the earth, and of the whole world, to bring them together to the battle of that great day of God the Almighty; Lo, I do come as a thief; happy [is] he who is watching, and keeping his garments, that he may not walk naked, and the may see his unseemliness, and they did bring them together to the place that is called in Hebrew Armageddon.
They GATHERED at Megiddo, the precise location where Titus forces were met with forces from Syria and from across the Euphrates River in Iraq led by foreign commanders. The war began up north, in Galilee. All surrounding Jewish villages were taken before Jerusalem was laid siege. Many Jews from these towns went to Jerusalem thinking they would be safe behind her massive walls. You have to study history too my friend, not just the Bible as the Bible does not contain dates.
We have angelic armies seen riding among the clouds in those days as recorded by Josephus:
a certain prodigious and incredible phenomenon appeared: I suppose the account of it would seem to be a fable, were it not related by those that saw it, and were not the events that followed it of so considerable a nature as to deserve such signals; for, before sun-setting, chariots and troops of soldiers in their armor were seen running about among the clouds, and surrounding of cities.
Is this anything you have heard of since 70 AD? Show me another secular writing which discusses an angelic army seen in the sky. I dare you. I double dare you. Everything fits the 70 AD time frame once you understand the language and realize that "world" is more literally translated "land" and you realize that the "known world" in that day where these words were written was limited to the Roman Empire. The disciples being sent out into all the world means they were to go throughout the Roman Empire, not the entire planet. Heck they didn't even finish going to every town in Israel before Christ returned. Paul claims they accomplished their mission before he died:
Read Col 1:23 if indeed you continue in the faith, grounded and steadfast, and are not moved away from the hope of the gospel which you heard, which was preached to every creature under heaven, of which I, Paul, became a minister.
Past tense - WAS PREACHED. We know none of them left the Roman Empire. Nobody went to China or the Americas. Nobody went to Russia.
What does Christ say in Mat 16?
Assuredly, I say to you, there are some standing here who shall not taste death till they see the Son of Man coming in His kingdom.
Are you also calling Christ a liar? Or, perhaps was He just being deceptive? Did none of them see Him come in His Kingdom? My view of His presence return in 70 AD fits, yours does not.