Trust me--I'm a mathematician.
Trust you?
You don't know some of the elementary concepts of geometry...
That's demonstrably wrong, of course.
...and you think you're a mathematician?
I know I am although you're obviously hoping I'm not.
Circles and squares are kinda like God. They only exist as abstract concepts. They're two dimensional things humans invented for their own purposes.
Yes. I know that.
Because they're both two dimensional...
Yes, I know that too.
...it isn't possible to put one on top of another.
Here's where you're going wrong. The possible positions of a square relative to a circle depends on the space they're in. On a plane in R2, yes, it isn't defined for any point on a figure to be "on top" of another point. However, in R3 a point in a sense can be on top of another. For example, P = (1, 2, 3) is above the point Q = (1, 2, 0). In a similar way, the circle having all points at z = 3 is "on top of" the square whose corner points are (3, 0, 0), (0, 3, 0), (-3, 0, 0) and (0, -3, 0).
One who doesn't understand that might think that drawing a picture, superimposing two shapes, represents the reality, but it doesn't.
You need to admit that you are wrong here.
Any more than superimposing God onto nontheists represents reality.
You need to consider all possibilities and not just what you think advances your beliefs.