Some Christians boast of wisdom and understanding so that they know God
and the secret of the kingdom of heaven and are saved. Do they?
I don’t think so. Here are evidences that they don’t know God nor the secret of the kingdom of heaven.
They will result in destruction according to the Bible
as long as they don’t learn wisdom and understanding from God.

Eph 1:7~8 In him we have redemption through his blood, the forgiveness of sins,
in accordance with the riches of God's grace that he lavished on us with all wisdom and understanding.

God lavishes on those who have redemption through God’s blood and the forgiveness of sin
with all wisdom and understanding.
Thus even if they boast of wisdom and understanding, where does come from?
It is because they never know what God’s blood is and how they receive the forgiveness of sins.

Here is another evidence that they have no wisdom and understanding.

Mt 13:11~12 He replied, “The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them.
Though seeing, they do not see; though hearing, they do not hear or understand.”

Why would it happen?
Even though they’re seeing but they don’t see the true Savior.
Although they’re hearing but they don’t hear the God’s voice.
Even if they’re thinking but they don’t understand that why God Elohim had to come in the flesh.

Isa 29:13~14 The Lord says: “These people come near to me with their mouth and honor me with their lips,
but their hearts are far from me.
heir worship of me is made up only of rules taught by men.
Therefore once more I will astound these people with wonder upon wonder;
the wisdom of the wise will perish, the intelligence of the intelligent will vanish.”

Unless they, who boast of wisdom and understand,
throw away the bad habit to honor God with their lips by keeping the rules taught by men,
God will take away wisdom and intelligence[understanding] and hide God’s face from them not to saved.