Herein lies the error...
It is not only true but totally logical and in keeping with the Scripture.
Both 'logic' and 'faith' are necessary forms of reasoning that may be applied to the endeavor to obtain a proper understanding of scripture. However, they do not mix
- each has its [own] 'realm' of operation - and, each must be applied as such - 'logic' to its realm and 'faith' to its realm. (There is one possible exception to this; however, I am not including it in the discussion of this post.)
Too many people try to "figure out" scripture by applying 'logic' to everything they read in scripture.
"That is their first mistake..."
When dealing with the 'spiritual' things in scripture, faith must
be the form of reasoning used. When dealing with the 'physical' description, etc. of things in scripture, then logic
may be used - inasmuch as those things are within the realm of 'logic'.
1. The "twinkling of an eye" is simply another way of saying "in the fraction of a second" or "in a moment" or "in a nanosecond".
I do not disagree.
2. This term applies to the resurrection of the saints AS WELL AS to the Rapture: 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. (1 Cor 15:52).
You do not understand the 'grammar of the language'. And, you left out the previous verse, which is vitally important in this case.
1 Corinthians 15:
51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, 52 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.
The part I highlighted in the orange color "goes together" as a single-thought-action in regard to the 'event' being described; however, it has no [direct] defining effect whatsoever
on what is after the colon (along with the word 'for') - because, the "thought context" has changed/shifted. The only
thing upon which the highlighted portion of these verses has any direct 'definition' is the highlighted portion itself - it does not
[directly] apply to anything else.
'we shall all be changed' is the 'event'
'In a moment, in the twinkling of an eye, at the last trump' describes 'details' associated with the 'event'
Now, it is certainly associated with - and aligned with - the ending phrase of verse 52. As such, it applies to that ending phrase - but only
that phrase. In other words, 'In a moment, in the twinkling of an eye' applies only
to 'and we shall be changed' - but, not
to any other part of the verse after the colon.
In 'event' terms:
[for] the trumpet shall sound,
[and] the dead shall be raised incorruptable,
[and] we shall be changed
Only the last one is associated with 'In a moment, in the twinkling of an eye'.
3. There are two events mentioned above:  the Resurrection and [2} the Rapture. So in fact that is ONE EVENT which should really be called "The Resurrection/Rapture of the Church".
I believe that there are three 'sub-events' in the overall event:
1) the Resurrection - the raising of the dead saints ('raised incorruptable' does not necessarily include the "change")
2) the "change" - all of the saints receive their glorified body together - the raised dead and the still alive
3) the Rapture - the "catching up" of all of the saints
However, it is certainly nothing to split hairs over...
4. To further confirm that this is true we have this statement: 16 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and  the dead in Christ shall rise first: 17  Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. (1 Thess 4:16,17)
Be careful not to include things it does not actually say.
Now the real issue is whether you will give up your delusional thinking in view of these clear Scriptures. Sadly people cling to their delusions more strongly that clinging to the truth.
No - the real issue is whether or not you are willing to temporarily 'suspend' all-that-you-think-you-know about the End Times Scenario and study the scriptures without "clinging to" the "assumed facts" foundation that you were taught to never-give-up-no-matter-what. (PRIDE is the 'concrete' that holds it in place.)
You and others do not even realize that you are wrapping scripture around a concept/idea that has been planted deep in your subconscience.
What you are thinking of as "clear proof" in this situation does not actually come "straight out" of scripture - it comes "straight out" of that deep-seated concept/idea
- which you have been subconsciously taught to "protect" at-all-costs by wrapping whatever scripture around it that may be considered to be in support of it.
I know this is hard for you to believe; however, you would do well to consider it - for your own sake, as well as that of others you may be inclined to teach.