The most-upvoted answer to that question is a great example of discussing mathematics as opposed to doing mathematics. The meat of the answer is
[T]he real problem is not so much nonrenormalizability as high-energy behavior inconsistent with local quantum field theory. ... With gravity, this high-energy/short-distance correspondence breaks down. ... This tells us that quantum gravity, at very high energies, is not a quantum field theory in the traditional sense.
The problem with demanding "an equation" is that each sentence in this brief summary concerns concepts that require years of study to answer in a mathematically rigorous way. What's meant by "a quantum field theory in the traditional sense?" by "nonrenormalizability"? by "high-energy/short-distance correspondence"? The existing answer does a nice job of explaining these, but much more depth is really beyond the scope of what this site can do in a single post.
Now, if you have a question about one of those specific issues, you might edit your question to clarify which one. But as it is, I think the other answer addresses your question.