whereunto
That is, made more sure by fulfilment in part. Fulfilled prophecy is a proof of inspiration because the Scripture predictions of future events were uttered so long before the events transpired that no merely human sagacity or foresight could have anticipated them, and these predictions are so detailed, minute, and specific, as to exclude the possibility that they were mere fortunate guesses.
Hundreds of predictions concerning Israel, the land of Canaan, Babylon, Assyria, Egypt, and numerous personages -- so ancient, so singular, so seemingly improbable, as well as so detailed and definite that no mortal could have anticipated them -- have been fulfilled by the elements, and by men who were ignorant of them, or who utterly disbelieved them, or who struggled with frantic desperation to avoid their fulfilment.
It is certain, therefore, that the Scriptures which contain them are inspired. "Prophecy came not in olden time by the will of man; but holy men of God spake as they were moved by the Holy Ghost". (2 Peter 1:21).
a more sure
Or, the word of prophecy made more sure.
dark place
Or, squalid place. (Psalms 119:105); (John 1:4); (John 1:9).