So you’re wrong about John and Paul being Gnostics. What you just wrote contradicts what they wrote and testified concerning Jesus.
It would be nice if you'd occasionally read what the text of the NT actually says.
This is Paul on Jesus pre-existing in heaven and creating the material universe:
1 Corinthians 8:6 yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
And this is the author of John on Jesus pre-existing in heaven and creating the material universe:
John 1:2 He was in the beginning with God; 3 all things were made through him, and without him was not anything made that was made.
And that is what in gnosticism the demiurge does.
None of which is found in Mark, Matthew or Luke.