That Jehovah's Witnesses booklet I have addresses this question. All I can say is - nailed it!
Was There Really a Global Flood? Many critics say No. But the Bible says Yes. Jesus Christ himself spoke of it, and he was alive when it occurred, viewing it from the heavens.
I must bow to these epistemological wizards. By the way - that's it. That's the entirety of this little factoid thing in the booklet. This is what Jehovah's Witnesses really believe counts as demonstrating claims.
Let's go through this a bit.
Many Critics say No.
Many critics? You mean paleontologists, geologists, oceanography, physicists, historians, archaeologists, whateverologists, etc? Those experts who actually have the thousands of man/woman hours spent gathering unfathomable amounts of data, and are in a position to know, to a great deal of detail, the history of the planet?
But the Bible says Yes
Oh! I'm glad we got that settled! A dusty old book says there was. Need we say any more? Nevermind that it flies in the face of the sum total of human knowledge, violates more laws of physics than we can shake a fist at, and is not supported by empirical or historical evidence.
Book says so. Done.
Jesus Christ himself spoke of it, and he was alive when it occurred, viewing it from the heavens.
Color me surprised that a character in a book might speak of events that took place earlier in the book. How can that be!? They don't cite a verse or anything, but I'll go along with that.
The assertion that Jesus was alive, however, doesn't really jive with Christian doctrine, as far as I know. Now I demand a verse citation. This isn't important to establishing the truth of the overall claim, but I'd still like to be pedantic for a moment.
So let me get this straight. While God was trying to fix one of his failures by using a flood (because apparently that's a better approach to violate everyone's free will by drowning them, instead of just snapping his fingers and resetting everyone's personalities), he already had created his demigod clone in anticipation of having to fix his next fuck-up?
Now, that's a guy who plans ahead.