a.) What did the LORD Jesus Christ Say about this very thing in His Gospel?
b.) What did the Apostles say about this very thing in their letters?
c.) At what point in our Salvation in Christ, while on earth, do we obtain perfect knowledge of all things?
Nobody ever remotely suggested that we obtain "perfect knowledge of all things". When you have to argue by using straw men, you know you're in trouble.
Look.... I've asked this question numerous times now and haven't gotten anything remotely resembling a decent answer. I'll try again though.
God wants us to know truth. 1 Timothy 2:4 - God "desires all people to be saved and to come to the knowledge of the truth." We know there's an enemy who seeks to deceive, even the elect (Matt 24:24).
There are so many amazing things to learn about the world we live in. So many truths for us to know. In fairly recent times, we have discovered the speed of light, learned how to split atoms, learned how neural networks work in the brain, observed molecular machines that put modern equipment to shame, built machines to go safely to the bottom of the ocean, travel many times faster than the speed of sound, learned how to cure all sorts of diseases, found ways to replace human organs, and even decoded the language of life: DNA.
We've developed technology that allows even you, a flat-earth guy, to pick up his phone and know EXACTLY where on earth you are at any moment, and can give you precise directions to get in your car and arrive at a destination that takes days to get there. Like, from exact spot on earth A to exact spot on earth B.
It would seem to please God to show us all this truth, since He desires for people to be saved and come to the knowledge of the truth. It may anger Satan that we have learned all this truth. Or maybe it doesn't, since his desire is to thwart the redemptive plan of God. He doesn't mind if we discover truth and are successful in the process IF that takes us off track in terms of God's redemptive plan.
Satan seems powerless to keep us from discovering DNA and molecular machines and all that stuff I mentioned above. Either that or he doesn't care about us knowing that so he doesn't work to keep us from knowing. Either that or God has overcome Satan and let us learn this stuff anyway. None of that is truth related to salvation anyway.
So why, oh WHY, does Satan care SO MUCH about the freaking SHAPE OF THE EARTH? You and I have already agreed that the shape of the earth is utterly IRRELEVANT to salvation. And Satan's goal is to thwart the redemptive plan of God. He seems quite content to let humanity know truth about the world as long as it doesn't affect salvation. So why is THIS one so dang important to Satan?
What makes THIS such a priority for Satan? We've both agreed that if we all believed the world was flat, Satan would still be actively trying to prevent people from getting saved anyway. So the shape of the earth literally has nothing to do with salvation, God's redemptive plan, or Satan's work to deceive people from knowing God. Can you give me a good reason why this would matter so much to Satan?