I'll put in my two cents. The idea of the flat Earth isn't thretening, but infuriating to me when the FE'ers as much as make the accusation, "The teacher shown you a globe when you were a kid and then you believed it without questioning". For someone into science and mathematics as I am, that's extremely insulting. I can prove the Earth is round by a schoolboy's ruler and protractor -- I make sundials in which the mathematics are based on a spherical Earth. So, I can calculate any weird contorted shape and roof surface and make a sundial for that part of the Earth and it will work here and there. So I will spare people the proofs of ships sinking below the horizon and pictures from space. I will take simple geometric principles and thus show why a flat earth and a sun only 3000 miles away is sheer nonsense. They are simple concepts in measurement, angle and perspective that anyone can do without all the complex calculations like I can do.
As for the Bible, as many times as I read thru it forward and backwards and forward more times than I can count, I do not find anywhere that states the shape of the Earth. The closest thing is Isaiah's "circle of the Earth" which can be interpreted as one's vantage point from the surface, as in a planetarium, where the horizon is all around you. That appears as a (horizontal) circle in which the Lord sits above from above that surface, i.e. the Lord is higher and mightier than anything on earth - it's not a verse about its shape. Then you have the "4 corners" argument. Well, first off, why do the FE'ers then say its a disk instead of flat square? And if one wants to talk about 4 corners, have we ever considered an inscribed tetrahedron within the sphere? A tetrahedron has 4 vertices, and divides a sphere up into 4 equilateral surface triangles. So a sphere can have "4-corners".
Now that I brought forth some geometric/mathematical concepts, I don't want to hear again that I believe the earth is a sphere "because I was told" and then I went duh... must be. Rather, I introduced some concepts here of my own thinking that is far more involved than I ever heard any FE'er state.