But when you screen capture and draw a line using MS Paint.

You notice how the horizon at the center of the line is above it, but at the ends it even with the line?
Well, sure, there will always be some apparent curvature when you look at a picture taken with a wide-angle lens.
Proving the Earth is round is not the same as proving the existence or non-existence of God. We stand on the Earth, we have sent crafts over the Earth. We have telecommunications systems based on the shape of the Earth. If we could see God or measure God's effects on the world, we could form an argument one way or another. But that just isn't the case. We can however make observations about the shape of the Earth.
I disagree with the former part of your response. I don't see how we could
ever know we were truly witnessing God, or His effect on the world.
As to the latter part, we certainly can. I have observed it countless times to be flat. But it didn't prove anything. Similarly, no matter how sure we were looking down on something that appeared to have curvature, we could never know for sure.
So you're saying there can't be evidence for a round planet, meaning no evidence that comes up would ever convince you of the planet's shape.
Not at all.
Ellipsis, I think I see where the confusion is.
Roundy is saying it's impossible because the Earth is Flat. As in it's impossible to present the evidence because it doesn't exist.
At least, that's what I think the confusion is. Am I right roundy?
No.