disregarding rapture timing, I fail to understand where the popular trope of just people suddenly vanishing into thin air that you see in well, virtually every movie depiction of a rapture ever comes from biblically.
In the most widely accepted "this is the rapture" passage, 1 Thessalonians 4:16-17
It's Jesus coming down from heaven, and there's a shout, the voice of an archangel, and a trumpet, it's not secret, it's pretty noisy, it's a big overt display.
But particularly pretribulation believers, depict it as just vanishing, No Jesus in the clouds, no shout, no trumpet, no Archangel.
They see it as people are going to not know what just happened and be confused, where, biblically, it would be pretty obvious when you have Jesus in the clouds and every eye sees Him.
In Revelation, during the wrath of God, it doesn't say that people are confused and don't know what happened.
Revelation 6:15-17
These people know exactly who caused these events and that there's more to come.
Revelation 16:8-9
Revelation 16:21
The people aren't deceived into some Alien abduction theory or other common ideas about how the rapture is going to be "explained away". They know what happened and who's responsible and instead of repenting they curse God.
Whatever your rapture timing, it's clear in the bible that the rapture is not secret but very out in the open and people know the cause and what comes next.
I just don't understand how people come to the idea that it is a secret that needs to be explained away.
While we do not know with 100% certainty if the Pre-Trib Rapture is visible for all to see or secret, the idea that believers vanish is definitely within the realm of possibility. For one, Jesus said this:
“For when they shall rise from the dead, they neither marry, nor are given in marriage; but are as the angels which are in heaven.” (Mark 12:25).
In other words, we will receive the body like that of angels in the Rapture. Angels can appear to be invisible to other people. The donkey had seen the angel of the Lord but Balaam did not
initially see the angel until later (See: Numbers 22:22-31).
The apostle Paul says,
“There is a natural body,
and there is a spiritual body.”
(1 Corinthians 15:44).
Paul also says,
“It is sown a natural body;
it is raised a spiritual body.”
(1 Corinthians 15:44).
Paul also says,
“Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed. For this corruptible must put on incorruption, and this mortal must put on immortality. So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality,...” (1 Corinthians 15:51-54).
Nothing is said as to whether unbelievers will hear the trumpet call or not. But it definitely is possible that they may hear something but they will not know exactly what it is.
For example, we read in Scripture:
“Father, glorify thy name. Then came there a voice from heaven, saying, I have both glorified it, and will glorify it again. The people therefore, that stood by, and heard it, said that it thundered: others said, An angel spake to him. Jesus answered and said, This voice came not because of me, but for your sakes.” (John 12:28-30).
In this instance some people heard God speak but they thought it was an angel speaking. Other people heard what they thought was the sound of thunder. Is it possible that the same thing could happen with the noise of the trumpet during the rapture? I would say, “yes.” It certainly is a possibility. People may hear a noise during the Rapture, but they may have no idea what it was. Notice what other men had heard during Saul's encounter with Christ whereby the Lord Jesus spoke to Saul (Paul) while others were with him.
“And it came to pass, that, as I made my journey, and was come nigh unto Damascus about noon, suddenly there shone from heaven a great light round about me. And I fell unto the ground, and heard a voice saying unto me, Saul, Saul, why persecutest thou me? And I answered, Who art thou, Lord? And he said unto me, I am Jesus of Nazareth, whom thou persecutest. And they that were with me saw indeed the light, and were afraid; but they heard not the voice of him that spake to me.” (Acts of the Apostles 22:6-9).
Is it possible that Jesus coming down to meet believers in the air is only visible to the body of believers that meet Him?
Well, Jesus was able to vanish in the crowd
“...but Jesus hid himself, and went out of the temple, going through the midst of them, and so passed by.” (John 8:59).
Jesus disappears in front of his disciples.
“And it came to pass, as he sat at meat with them, he took bread, and blessed it, and brake, and gave to them. And their eyes were opened, and they knew him; and he vanished out of their sight.” (Luke 24:30-31).
So yes. The Pre-Trib Rapture can most definitely be a secret from the rest of the unbelieving world. For there is nothing in Scripture stating the Rapture event must be visible and clearly heard by unbelievers.
I hope this helps, and may God bless you.