Astargath upthread you challenged Perry Marshals argument on the applicability of applying "Godel's incompleteness theorem to systems beyond mathematics.

His essay can be found here:
The #1 Mathematical Discovery of the 20th Century

Specifically you asked.

"And how do you know Perry Marshal is right? "
and
"How did you determine that what he said is right?"

You then go on to challenge his use of the word coherence and quoted a couple of half hearted challenges to Perry Marshal's logic.

Clearly you could use your a little help here so I will give you a hand. It is indeed possible to challenge the logic behind Perry Marshal's essay but you have to use actual logic to do so.

Sometimes you can still find a rational and logical atheist. John Gould over at Quora appears to be such an atheist and he appears to understand logic. If you truly want to understand how to challenge Perry Marshal's argument consider taking the time to understand his challenge.

https://www.quora.com/Can-Gödels-incompleteness-theorem-applied-to-the-universe-prove-the-existence-of-God

What John Gould shows is that Godel's incompleteness theorem can also lead to a second possibility that deity is an undisprovable falsehood.

This juxtaposition of necessary truth versus undisprovable falsehood may be as far as logic can ever take us if the universe is indeed incomplete. It is possible that logic can only show us that it is coherent and logical to believe in God. To actually internalize and live by that logic requires faith.

My own opinion is that this fundamental bifurcation this necessity for faith persists as we climb towards perfection. Perhaps there will always be a need for faith and this fundamental spiritual struggle scales in difficulty matching future growth in intellect and ability.

This persistent need for faith as we grow closer to perfection may also be the answer to your question above.  Why might a being approaching perfection throw that perfection away? Said being may simply have lost faith.

In regards to your questioning the word coherence and how to ultimately determine right or truth. These are very deep topics.

There are several philosophical theories of truth. The most known are the correspondence theory of truth, the pragmatic theories of truth, and the coherence theory of truth since you are interested in coherence I recommend reading up on this third theory.

A brief summary of these theories can be found here.

Truth, Theories of
http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/truth-theories