Where does it actually say those things, inparticular Mark saying anything?

It just takes faith.

We really don't know who they were. The best we've got to work with is that SOMEONE wrote the stories, for they are written, after all. And signed, but that doesn't identify the writers, absent any historical reference outside the Bible itself. Anyone can sign any name. I have published articles under several pseudonyms, including Cincinnatus. A signature proves nothing. But we do know that they didn't write those stories until twenty to forty years AFTER the events had happened. And by their own admissions, the writers were not even present when most of those events DID happen. The scriptures that were finally gathered up to make the Bible were copies of copies of copies of.... The Bible was CREATED in AD 325, and every "book" in it had to be chosen by a majority VOTE. And even then, only after one bishop poisoned another who disagreed with him. More Holy Scriptures were left out than were included. So I don't "hold it to be true." For me, both Testaments are works of fiction. Memorable and magnificent masterworks, many of them, but still fiction. You may say all the writers were inspired by some god or other. So? Every writer who writes any work of fiction is inspired, even the three-year-old who wrote, "The cat Went up the sky of gold, Went up the sky of blue. The gold was very gold, The sky was silver blue."

(Rom 14:23) And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin.

Yes, I believe God set the stage for it all to take place so that we may have the opportunity to understand His truth that never changes. So when "Mark said, Peter said"..is like you and me asking very human questions or reacting a certain way and then we see how these are Divinely answered, setting our minds free from our self-centered torments. When we start to "get it", you can't help but to start to fall in love with Him.

Faith is a funny thing that makes you believe all unreasonable things for which there is no proof whilst making you disbelieve all reasonable things for which there is plenty of proof of

I assume you're trying to discredit the Gospels? Matthew and Luke were literate. There is no reason to assume they didn't write what they wrote. But if a message is dictated to a scribe, who is the real author? the one who generated the words, or the one who wrote them down? Yes, we can tell that the words are inspired simply because they have helped so many over so many years. And if there is any 'proof' of sections of the Bible that were deleted because they were not helpful, I'd love to see it. Making wild claims that serious researchers laugh at is no way to discredit anything. We have ancient copies of scriptures which are identical to what we currently possess. The 'they copied it wrong' argument is specious at best.

Just for the sake of the argument; "..How do we hold these things to be true if we don't even know who were they were?" The works of Aristotle, Newton, Shakespeare, etc, are considered to be timeless masterpieces containing universal truths of enormous value to mankind. If the names of the authors of these works were not known does that invalidate the works per se?