John 14:1 (NIV)
Trust in God, trust also in Me.
It's easy to believe God but it's impossible to believe that Jesus is God. A man may believe in a higher, cosmic, supernatural being whom he has never seen. But unless that man has received a revelation from our Heavenly Father, there is no way that he will accept Christ as Lord. Men are not sent to hell because they don't believe God but because they don't believe that Jesus is that God.