It is not correct to assert this. More precise is to say: it is unlikely that all of the gospels were written by the names we now associate with them -- at least not insofar as these names relate to the 12 disciples.
The truth is we don't know who wrote the gospels. The evidence is that they are quite early (i.e. for Mark, consensus is late 60s so perhaps 30-40 years after Jesus' death). In fact, many scholars think 'Mark' was written by 'Mark Antony' who is mentioned in Acts. And John may have been written by a 'John the Elder' who is mentioned elsewhere. These are educated guesses though -- the evidence is circumstantial.
> [Our] truth is we don't know who wrote the gospels
Okay, because y’all forgot? People purposely want to remake Sacred Scripture?
I mean, the Church knows who wrote them; Jesus, Mary and the Saints know; bishops and priests and the faithful knew for centuries.
Naming of Bible books isn’t about some guy holding a pen and making stuff up: the names speak to provenance, lineage, and perspective. Somewhat the same function as the “begat” passages everyone hates (because who can remember who all THOSE people were???)
If scholarship wants to move past that attribution and unmoor the books from tradition, then they can. Modern interpretations, perspectives, and hermeneutics are always in demand. But I confidently assure you that anyone who mattered was well aware of where those books came from and “who” had written them, notwithstanding meddlesome medieval monkey business.
This is bit besides the point, but I'll stick it here anyway.
When I read <u>A Man Called Ove</u> in English I was impressed over and over again with the writing. It made me wish I could understand Swedish to compare the original prose. I concluded that Henning Koch is an amazingly talented wordsmith. And it made me suspect that Fredrik Backman might also be one. Clearly, Backman is a very good writer. But I wonder if Koch is a better wordsmith. Sadly, I am unable to enjoy Backman in the original language. As it is, I credit Backman with great writing and Koch with great wording (probably inspired by Backman's great wording).
The truth is we don't know who wrote the gospels. The evidence is that they are quite early (i.e. for Mark, consensus is late 60s so perhaps 30-40 years after Jesus' death). In fact, many scholars think 'Mark' was written by 'Mark Antony' who is mentioned in Acts. And John may have been written by a 'John the Elder' who is mentioned elsewhere. These are educated guesses though -- the evidence is circumstantial.