I believe your sentence is correct and means what you want it to mean, but I would omit the comma because the that clause is important to understanding what "it" is. "It" is something like "the belief":Thank y'all for your answers. Really appreciated. But, I am still not clear. I have been thinking over this question, for days. I am really obsessed with this grammar problem, and I really need your help
So... you've asked the source of the quote! I provided it in the thread but a mod found it inappropriate and then deleted it. It's OK. No critique, no judging, no whining
For example, I want to ask if X Forum (let's say "WordReference Forums") has the most educated community on the internet. But, I don't know what I can base my claim upon. So, I ask a question like that: "What are we basing it upon, that we can say this?" (this = X Forum has the most educated community)
owlman5 said the sentence wouldn't work without "that". So, can I construct the same sentence as follows: "By basing it upon what, can we say this?"
a mod found it inappropriate and then deleted it.