I think if you read more than just a snippet of Elaine Pagels work you will find a greater deal. I have. I have studied the origins of Christianity for many, many years and haven't been selective on authors.
Catholicism still recognises the book of Revelations, it was selected and adopted, but excluded the gospel of Jesus, of Mary and Thomas. All existing documents found at Nag Hammadi. The bible isn't the word of God. The bible is an adopted series of stories from other religions prior to Judaism. The subsequent 'new testament' is a political theosophy similar to Islam and is capitalist and exclusionist equally.
As for gnosticism, well, if you delve into it you will find that is as different to Christianity as it could be, save for the Cathars and Bogomils and theirs was an amalgamated faith drawing from the heretical orthodoxies of Turkey that included a different form of 'christianity' that doesn't recognise any of the catholic traits.
You are making no sense either. I am pointing out that the adopted beliefs of existing Christianity and its origins have absolutely no relevance to Islam shaping any destiny in Europe and the fearmongering of immigration adopted by the Brexit campaign as its lead justification is, shall we say, un-christian?