Which fear of God?
The wisdom of “its wise” (their wise – who taught the teachings of men) will perish.
Who are these?
One more clue: These ones taught a “fear” towards God. In the New Testament Christ quotes these verses to refer to the Pharisees & Sadducees (included as one of the scribes – Matthew 15:1).
Thus it must refer to which “fear of God” they taught the masses that is, “eternal hell” from the Pharisees and “annihilation” from the Sadducees (literally).
Can you see these false teachings by men and how God had prophesied that “its wisdom/their wisdom” (of both eternal hell & annihilation, deductively) shall perish?
Another secret of Scripture revealed. Here are these verses which testify to this truth “literally”:
“And the Lord saith: Because drawn near hath this people, with its mouth, And with its lips they have honoured Me, And its heart it hath put far off from Me, And their fear of Me is — A precept of men is taught!
Therefore, lo, I am adding to do wonderfully with this people, A wonder, and a marvel, And perished hath the wisdom of its wise ones, And the understanding of its intelligent ones hideth itself.’.”
(Isaiah 29:13 – 14)
Here is our Blessed Lord quoting them (or referring to them) “literally”:
“Hypocrites, well did Isaiah prophesy of you, saying,
This people doth draw nigh to Me with their mouth, and with the lips it doth honour Me, but their heart is far off from Me;
and in vain do they worship Me, teaching teachings — commands of men.’.” (Matthew 15:7 – 9)
Note the word “hypocrites” too.