Paul is not referring to the Seventh Trumpet of Revelation. He didn't even know about Revelation, as he was likely dead by the time John wrote it.
It is sheer nonsense to say those 2 Trumpets are the same.
First...
how many "last Trumps" do you imagine there are?
Of course
there is only ONE last Trump. Since the "last Trump"
in 1 Co 15 includes the resurrection of the dead and the destruction
of Satan and DEATH... do you REALLY imagine there is ANOTHER
Trumpet after that? How can I take you seriously when you
say such things?
1Co 15:51-55
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,
then shall be brought to pass
the saying that is written, Death is swallowed up in victory.
O death, where is thy sting? O grave, where is thy victory?
Second... and I am very surprised that you would say this because
to think Paul was writing on his own is blasphemy... Paul did not need
to see John's writings... because Paul was writing under the inspiration of the Holy Spirit. Paul was NOT writing based on what he read from John or anyone else. In fact, it is likely that Paul did not even know
the WHEN or WHERE of what he said about the Last Trump
2Pe 1:20-21
Knowing this first, that
no prophecy of the scripture
is of any private interpretation. For the prophecy came not in
old time by the will of man: but holy men of God spake as they
were moved by the Holy Ghost.
2Ti 3:16-17
All scripture is given by inspiration of God, and is profitable
for doctrine, for reproof, for correction, for instruction in
righteousness: That the man of God may be perfect, throughly
furnished unto all good works.
Finally... it seems you say "it is sheer nonsense" to everyone
who corrects you. Do you imagine the verses above are just
"sheer nonsense". Do you REALLY image there is ANOTHER
"last Trump" AFTER the resurrection and destruction of Satan
and DEATH? Where is your Scripture to support such a view.
Saying "sheer nonsense" is NOT a substitution for Scripture.
And you already KNOW that fact.
.