@ CB, OMG man - I am not arguing evidence here or an effect of looking at a lake; you did not see the globe as a whole and probably will never do!
An astronaut belongs to the space agency that showed you the evidence and is not an individual like you and I.
He saw the ball and Nasa did, but not you and I or billions of other people.
Until FE have an agency of their own that can show us endless land everywhere from space, we have to accept what space people tell us and show us.
You are 100% sure earth is a globe because you believe in the science that tells you so and trust the agency that showed you the evidence, and I respect that.
On the other hand, I cannot say I am 100% sure earth is flat just because holy books might've said so, or because of some videos over the net with no scientific support - I feel it flat, but I don't think that's enough to claim it is!
And we're never gonna see the ball... 
ok than tell me where did you see the flat earth as a full?
you are 100%sure that the earth is flat because you think all scientist that say the earth is a globe are lying without any prove of that.
you are 100%sure that the earth is flat because it is not clearly say in your fairy tail story book that the earth is a globe (BTW neither it says that the earth is flat)
you are 100%sure that the earth is flat without one evidence and proof that you can show us.
I thought I could express myself well in English (even it's not my mother tongue), but obviously not with you CB!!!
Please read again what I stated, so I would not have to write it again.
I am supporting what you're saying, but I had to phrase it in a different way, so FE would understand that claims are not enough without physical observations, methods of testing planetary motion and the math the backs everything up.
I said, I cannot be 100% sure just based of faith > science is required in this case more than faith.
Where did I say I am 100% sure - you repeated that 3 times >
I never saw the earth flat as a full and you never saw the earth a globe as a full > so, let's stop playing Tom & Jerry and be more realistic here.
Only space agencies did see the shape of the earth in reality, but obviously there is a BIG question mark raised against them from FE, and I don't really know what started it all!
We were doing fine with Nasa until we saw many fingers pointing at them from all over the globe with many accusations of faking their entire program.
I myself questioned their program when I wore a FE shoe, but to be honest; I couldn't find one satisfying answer that could weaken their credibility and convince me that the whole-world' governments (enemies and allies) could be involved in this none-sense space conspiracy > I couldn't simply buy that, but I had to question that myself to be convinced otherwise.