If "one doesn't believe in God" then why would "one [want to] still be going to heaven?"
The Kingdom of Heaven is where the Kingom of God is located.
Simply put: I don't know anyone who goes to permanently live with someone they don't know...a stranger that is.
Bottom line: "No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him" (1 Corinthians 2:9).
Therefore the opposite must be true: "No eye has seen, no ear has heard, no mind has conceived what God does not have prepared for those who do not believe in Him".