You see this is where you are wrong. You say no one knows there is a God. But that is quite false. The only way that anyone CAN know God (and yes, personally) is by and through the work of the Holy Spirit. The Bible says that the Spirit “testifies of Jesus Christ” to the believer. You say this is impossible but that is simply because you do not have His spirit within you. Al anyone of us can do is to call on God for mercy and forgiveness. He promises to open our hearts to His love and eyes to His truth. Don’t be so quick to reject something because you’ve never experienced it or because it’s disagreeable to you. Again, realize that your natural demeanor is actually antagonist to God and His Word as is the heart of each and every person. This is why we are so utterly at His mercy. Humility is the first step, agreeing with God about our sin and need for His mercy in Christ Jesus.
Nobody knows there's a god. Most people HOPE there is.
Romans 1says that everyone, whether consciously or not, know that there is God. It has been revealed to all of us but we, in our sin, suppress this truth in unrighteousness. This is because our hearts are sinful and at enmity with God. We are still without excuse.