The secret of the LORD is for those who fear Him, and He will make them know His covenant (Ps. 25:14).
What secret does David mean? He answers, "Who is the person who fears the Lord? He will instruct him in the way he should choose" (Ps. 25:12).
The Hebrew sôd ('sōhd) translated as "secret"––also means "intimate council" and "counsel" or even "friendship." "The secret of the Lord" is the intimate counsel afforded to those who truly revere Him, and thus are afforded fellowship with Him.
Solomon wrote, "The fear of the LORD is the beginning of wisdom, and the knowledge of the Holy One is insight" (Pro. 9:10).
Without godly fear in one's heart there can be no intimate fellowship with God––there can be no real knowledge of His will. One may be "always learning but never able to come to a knowledge of the truth" because his heart is moved, not by reverence, but by "various passions" (2 Tim. 3:6-7).
God condemned the false prophets of Jeremiah's day for their pretended knowledge and fellowship: "They keep saying to those who despise Me, ‘The LORD says that you will have peace,’ and to everyone who walks in the stubbornness of his own heart, ‘No harm will come to you'" (Jer. 23:17).
Such can never partake of God's covenant––then or now. God calls out the fakers––they never stood in His sôd: "For who among them has stood in the COUNCIL of the LORD to see and to hear His word, or who has paid attention to His word and listened?" (Jer. 23:17).
So it is with Christ: "He who has My commandments and keeps them is the one who loves Me; and he who loves Me will be loved by My Father, and I will love him and will disclose Myself to him" (Jn. 14:21).