Assuming one were seraching for the 'signature' of God, one would expect to find it in bible text, and not the TV Guide, as an example.
Within the bible text then, try the same criteria on John 1:1-17 and see if you find the 'signature of God' there. No? Guess God didn't sign "John" then, so remove John from the Canon and next check Romans...
Nonsense.
No one is presuming to construe it that God signed every several verses of Scripture in a particular way.
God did however much of it that He did. He didn't have to meet our silly notions on how He OUGHT to have done it!
If one used only biblical writings, then one could simply set a low standard as evidence of the signature.
If one uses writing that it is absolutely agreed is not of divine origin (anything by Gore Vidal, for example :>), then one would have a baseline for comparing with recognized divine writings.