Didn't they know the earth was round in ancient Greece? I don't think any scientist have denied the world as being round in a looooong time.
yes. Yes they did. They even knew the circumference of the earth.
Guy in Egypt heard from a friend how when the sun was at it's height it shone directly down the village well.
Guy went "Wait, it doesn't do that here. What's going on?"
and so figured out the Earth had to be a sphere.
In short, science tested for evidence and then based it's views on that evidence.
Not something religion is well known for.