i do agree with a LOT of what you say.
Gnostics were around way before Jesus, so that part is true.
i still see literal accounts & it starting with a literal Jesus & the Apostles.
you are right on the mark with the politcal agenda. i think that all came down with doctrines & creeds to establish a religion of Christianity by the use of force through war & murder. anyone who disagreed was silenced & mudered.
while i also agree there was some tampering & plenty of evidence for it, i dont think they altered scripture enough to change the true meanings.
in doctrine, tradition, creeds & hymns, YES, it has been severly altered & stayed on track through force through the generations, starting from the time of birth right on through childhood.
i also agree that Pauls epistles were the less tampered with. where we disagree is on the book of Acts. I think Acts is also one of the purest books.
my 2 cents