Long reply. Sorry.

True Followers of Christ =/= every person who says that they are Christian.

I honestly don't know what you mean by =/=. But if you are saying that True Followers of Christ are or are mostly every person who says that they are Christian, I would disagree. The guys that I know considers themselves true christians because they try to do and act the way they think God want them to. They actually try to follow Christ, in a way. Most people who say they are Christian are that just in name, and not action.

Anyway..
Sure, religion-wise the why is more important. But that's also beside the point.

When I'm debating with my friends, they love to explain that the Bible is scientifically correct, that the Bible even say things that science have found to be true thousands of years later. It says that the earth is round and hangs on nothing, and it's specific about hygiene, just to mention a couple of things.

(I'll also respond to your other reply here.)

The Bible never states how old the earth is.

I know, and this isn't up for debate. But my friends, who holds the believes of the Jehovah's Witnesses, says that the Bible tell how old human kind is.(Something around 6000 years old.)

Keep in mind that my friends greatest wish is probably to turn me, to "save" me. I don't mind that. I find talking with them interesting.

They also keep talking about stuff that archeologists find. "They have found this and this and that, which corresponds with this this and that in these verses in the Bible. You see, the Bible is accurate and correct. Archeologists even say it's from the same time that the Bible says." Etc.

A lot of time goes in to proving the Bible, because if they can make people Believe in the Bible, they have a better foundation to teach the rest of their religion.

And so, this is why I find the questions in my OP interesting. When science clearly shows that things in the Bible, like the deluge, could not have happened the way the Bible claims, and also that their timeline is off.

But perhaps, given that the Bible is still somewhat historically correct, the deluge didn't engulf the whole earth, like someone else is pointing out here. It could have been the world as they knew it. Or a flood that seemed so big that such an exaggeration is in place? Idk.

On one hand my friends explain the Bible through science and more or less convincing arguments, and then, on the other hand, when it's something they can't explain, but they still believe it, the answer will be that "it's well within the power of God to do it."
What I'm thinking is "Well, maybe you are wrong. Maybe you have the wrong understanding. Maybe, given that you are right about other things, like the bible being from God etc, this wasn't to be taken litterally?"