Analogy: Researching Medical Advice

Questions about Greg placing his faith in his personal assessment of which truth claims best match reality rather than in the revelation of God in Jesus and a personal encounter with the Spirit, and how to fight thoughts that God isn’t real when you know he is real.  

• Please respond to this critique of Greg Koukl: “Those who place their faith in their personal assessment of which truth claims best correspond to reality are placing their faith in something other than the revelation of God in Jesus Christ and a personal encounter with the Holy Spirit.”
• I struggle with thoughts that God isn’t real even though I know he’s real. How do I fight this?