There is a difference in knowing God and knowing about God. Most people know about God from things they have observed or heard. Your parents may have talked to you about God. You may attend church to hear sermons about God. However, knowing about God is not knowing God.
The only way you can know God is by faith. He who comes to God must believe (Hebrews 11:6). You cannot come to God any other way. Because God is Spirit (John 4:24) you cannot see Him. Only faith can usher you into the presence of God.
The only way to know God is when He reveals Himself to your heart. When we say heart, we mean your mind, will, and emotions. God changes your heart through the gospel of Jesus Christ, that you can have faith to trust Him. If you know God, it's by faith, looking unto Jesus, the author and finisher of our faith (Hebrews 12:2).
If you know God, you can walk with God. He becomes your daily companion. You can only walk with God by faith. For we walk by faith, not by sight (2 Corinthians 5:7). Faith assures you that God is with you today, and everyday. Faith is the assurance that God hears your prayers. Faith is the evidence. When you know God, faith is the evidence of things not seen (Hebrews 11:1). If you know God, it's by faith.