By faith you can know God. Faith is sure, absolutely confident, that the Lord God Almighty rules over all. Faith will not listen to doubt nor unbelief. The reason is simple, faith has heard from God. Faith is assured of the truth found in God's covenant word. You see, "Faith comes by hearing, and hearing by the word of God" (Romans 10:17). Faith simply takes God at His everlasting word of promise.
Doubt can never be sure. No matter what doubt hears, there is never any certain assurance. Not only that, but doubt thinks no one else can really know that God is real. Doubt says, "Maybe God is real and maybe He's not. There are times I've thought He is, then again I think He's not." Doubt thinks those who say they believe in God are really just playing a religious game.
Unbelief is dogmatic. Unbelief says, "There is no God. It is ignorant and uneducated people who say they believe in God. How stupid. Show me the evidence. If there is a God, I would know it and understand." Unbelief lifts himself up in pride, looking down on others who believe.
By faith you can know God personally. Faith sees God at work. Faith recognizes God created all things. Faith knows God as Father, and Jesus as Lord and Savior. Faith knows love, because "God is love" (1 John 4:8). Faith lives with joy, because faith knows Christ. Faith knows peace, because faith knows the Holy Spirit. "But the fruit of the Spirit is love, joy, peace" (Galatians 5:22).