just dont bring it up
so he's trying to draw the correlation that because mathematics is invented by man/humans that it's the same thing as god being made up by humans/man? Because something is "mind dependent" then it can all be true just if we made it up? Since man made math up as well

very simplistic conclusion there lol
Difference here is mathematics can be proven so it's not really methaphysical.
"Mathematics is an abstract language describing reality's structure"
the reality of mathematics can be proven on a daily basis. The computer you type on now it's system language is based and built on mathematics. The money in your bank account it's counted for in a mathematical system.
God is not proven it's just conceptual thought people have.
Conceptual methaphysical vs Proven theory.
I mean I say that santa clause is real and that he will come flying with raindeers, come down the chimney and hand me the presents I've been wanting. It doesn't make it reality. If I say I still believe it adults will just think I'm etiher joking or I'm severly retarded to the level of a 5-6 year old(or probably lower). The thing with God is for me the same thing.