Space is a universal and immediate necessity for creation, since creation is finite. We have sufficient proof that finity or the finite exists, and then with logic we are able to further infer that there is also the infinite, which is quite different. So then we are to figure the relation between the two, the finite and the infinite.
The finite has sides, straight lines, curves, and divisions, whereas the infinite does not, but since it does have a relation to the finite it doe have a relation to these created things. Certain things from the finite would represent a relation to the infinite better than others. For instance, straight lines have an end and a beginning, and do not represent relation to the infinite as well as a circle, which does not have a beginning or ending, since the infinite is like a circle in that it does not have a beginning or ending.
So the Earth is at least a circle, and any circle that is also complete in 3-D becomes a sphere. Aristotle describes the very formation of the Earth as a spherical process, which I think reflects the Holy Trinity, which is also "3-D", yet in a very supernatural way. Therefore, I say that a flat Earth does less honor to the very sublime and supernatural nature of the Most Holy Trinity who are one in three ... even like a sphere.