Before reading my comments below I suggest reading my answer to a related question and also this one. In the first I discuss the context of Paul's apostolic authority being questioned because of his unsophisticated speech and in the second I explain the difference between "searchable" and "unsearchable".
Here I want to point out that while there are searchable and unsearchable things in the scripture, to the apostles who were in the new covenant they are all "searchable", yes even the extremely deep and the extremely high:
[Job 28:1-3, 7, 11-28 KJV] 1 Surely there is a vein for the silver, and a place for gold [where] they fine [it]. 2 Iron is taken out of the earth, and brass [is] molten [out of] the stone. 3 He setteth an end to darkness, and searcheth out all perfection: the stones of darkness, and the shadow of death. ... 7 [There is] a path which no fowl knoweth, and which the vulture's eye hath not seen: ... 11 He bindeth the floods from overflowing; and **[the thing that is] hid bringeth he forth to light. 12 But where shall wisdom be found? and where [is] the place of understanding? 13 Man knoweth not the price thereof; neither is it found in the land of the living. 14 The depth saith, It [is] not in me: and the sea saith, [It is] not with me. 15 It cannot be gotten for gold, neither shall silver be weighed [for] the price thereof. 16 It cannot be valued with the gold of Ophir, with the precious onyx, or the sapphire. 17 The gold and the crystal cannot equal it: and the exchange of it [shall not be for] jewels of fine gold. 18 No mention shall be made of coral, or of pearls: for the price of wisdom [is] above rubies. 19 The topaz of Ethiopia shall not equal it, neither shall it be valued with pure gold. 20 Whence then cometh wisdom? and where [is] the place of understanding? 21 Seeing it is hid from the eyes of all living, and kept close from the fowls of the air. 22 Destruction and death say, We have heard the fame thereof with our ears. 23 God understandeth the way thereof, and he knoweth the place thereof. 24 For he looketh to the ends of the earth, [and] seeth under the whole heaven; 25 To make the weight for the winds; and he weigheth the waters by measure. 26 When he made a decree for the rain, and a way for the lightning of the thunder: 27 Then did he see it, and declare it; he prepared it, yea, and searched it out. 28 And unto man he said, Behold, the fear of the Lord, that [is] wisdom; and to depart from evil [is] understanding.
Paul explains that since the believer is part of Christ's body and his body has a single breath, and since the breath is the seat of intelligence in a man, we share Christ's insights into the deep things of God. In this way Christ is "made to us wisdom".
[1Co 6:17 KJV] 17 But he that is joined unto the Lord is one spirit.
IE: All of the breath of the body is supplied from the head, through Christ's mouth:
[Eph 4:14-24 KJV] 14 That we [henceforth] be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, [and] cunning craftiness, whereby they lie in wait to deceive; 15 But speaking the truth in love, may grow up into him in all things, which is the head, [even] Christ: 16 From whom the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love. 17 This I say therefore, and testify in the Lord, that ye henceforth walk not as other Gentiles walk, in the vanity of their mind, 18 Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart: 19 Who being past feeling have given themselves over unto lasciviousness, to work all uncleanness with greediness. 20 But ye have not so learned Christ; 21 If so be that ye have heard him, and have been taught by him, as the truth is in Jesus: 22 That ye put off concerning the former conversation the old man, which is corrupt according to the deceitful lusts; 23 And be renewed in the spirit of your mind; 24 And that ye put on the new man, which after God is created in righteousness and true holiness.
- some things are past finding out and must be revealed:
[Pro 25:3 KJV] 3 The heaven for height, and the earth for depth, and the heart of kings [is] unsearchable.
[Isa 55:9 KJV] 9 For [as] the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts.
- the apostles, all Jews, were among the 144,000 beneficiaries of the new covenant with the houses of Israel. One of the features of that covenant is that they would know God's instruction without any man teaching them:
[Jer 31:34 KJV] 34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
Paul explains that this hidden wisdom was ordained to give splendor to their teaching which comes out of their decrepit clay vessels:
[Phl 3:8 KJV] 8 Yea doubtless, and I count all things [but] loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them [but] dung, that I may win Christ,
[2Co 4:11-12 KJV] 11 For we which live are alway delivered unto death for Jesus' sake, that the life also of Jesus might be made manifest in our mortal flesh. 12 So then death worketh in us [IE: the apostles], but life in you.
So we see that Paul is saying that just as a man is made self aware by the spirit/breath within him so those who have the anointing of the spirit know all of the things of God (that they need to know) by the self-awareness of those in Christ. By having the spirit they have the knowledge of God:
Those, likewise who are anointed "know all things":
[1Co 2:9-16 ESV] 9 But, as it is written, "What no eye has seen, nor ear heard, nor the heart of man imagined, what God has prepared for those who love him"-- 10 these things God has revealed to us [IE: the apostles] through the Spirit. For the Spirit searches everything, even the depths of God. 11 For who knows a person's thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God. 12 Now we [IE: the apostles] have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God. 13 And we impart this in words not taught by human wisdom but taught by the Spirit, interpreting spiritual truths to those who are spiritual. 14 The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned. 15 The spiritual person judges all things, but is himself to be judged by no one. 16 "For who has understood the mind of the Lord so as to instruct him?" But we have the mind of Christ.
YLT 1 John 2:20 And ye have an anointing from the Holy One, and have known all things;