It is one thing to know about God and an entirely different thing to Him. However,  God wants you to know Him, not just to know about Him. This is one of the foremost desires of His heart. Jesus even describes eternal life as: to know God (Jn 17 :3). God expresses this desire in Jeremiah chapter 9:23, 24, “Thus says the Lord: “Let not the wise man glory in his wisdom, Let not the mighty man glory in his might, Nor let the rich man glory in his riches; But let him who glories glory in this, That he understands and knows Me, That I am the Lord, exercising lovingkindness, judgment, and righteousness in the earth. For in these I delight,” says the Lord.” The only thing God permits you to glory in is that you know Him.
    However, we can only know God by revelation. If God does not reveal Himself to man, it is impossible for him to know God. No amount of intellectual prowess is enough to make you know God, apart from His revealing Himself to you, for the Scripture says, “…the world through wisdom did not know God,…” (1Cor 1:21). That was also why Paul the apostle said, “And my speech and my preaching were not with persuasive words of human wisdom…” (1Cor 2:4). The apostle had realized that in spite of his intellectual attainment as a Pharisee (for he had described himself as a Pharisee; Philp 3:5), he completely failed to know God. Revelation can be defined as the act of  disclosing or unveiling something. This experience can either be sudden or gradual. It is the sudden or gradual realization of a reality, that the HolySpirit discloses or unveils to you. 
    A good Biblical illustration of the point made above is prophet Samuel. As a boy under Eli’s tutelage, Samuel had on certain occasions mistaken God’s voice for Eli’s. The reason for that, the Bible says is: “Now Samuel did not yet know the LORD: The word of the LORD had not yet been revealed to him.”(1Sam 3:7 NIV). Though Samuel lived in close proximity to the ark of God, the text above shows that he did not know God because He had not yet been revealed to him. However, as time went on, God revealed Himself to Samuel: “The LORD continued to appear at Shiloh, and there he revealed himself to Samuel through his word.” (1Sam 3:21 NIV). Only God can make Himself known to man.
    It is significant to note that God reveals Himself through His word, as 1Samuel 3:21 shows. God must speak in one way or another before mankind can know Him. This is why the Bible says, “God, who at various times and in various ways spoke in time past to the fathers by the prophets,” (Heb 1:1). Communication has been God’s method of revealing Himself to man, from time imemorial. He made Himself known to the fathers through prophetic words. In fact, following the revelation of Himself to Samuel, the Bible says, “And the word of Samuel came to all Israel.” (1Sam 4:1). Until God had revealed Himself to Samuel through his word, Samuel’s word did not reach Israel. The reason for that was that God’s word was supposed to become Samuel’s word. If the content of God’s word to Samuel was the revelation of God’s person, then the content of Samuel’s word to Israel must be the revelation of God also. God reveals Himself first to us so that He can do the same thing through us to others. That was why Paul said : “But when it pleased God, who separated me from my mother’s womb and called me through His grace, to reveal His Son in me, that I might preach Him among the Gentiles, I did not immediately confer with flesh and blood,” (Gal 1:15,16). Until ‘His Son’ was revealed to Paul, he could not preach ‘Him.’ Any attempt to know God apart from revelation knowledge is an exercise in futility. Shalom.