It does take a certain amount of faith to believe in God. "You can't argue someone into heaven" will always be true and it always has been. If someone does not choose of their own free will to believe in God or His son's sacrifice, then there's really nothing anyone else can do about it. Even making someone "fear" what will happen to them if they don't convert is missing the whole point of Christianity.
It is said several times in the Bible that God loves ALL of His creation (John 3:16 for one.) The reason for their being a heaven and hell is two fold. First off, Heaven is where God resides although His influence extends easily to earth. With the goal of keeping it sinless, only those who have accepted Jesus Christ's sacrifice as an atonement for their sins will be allowed into the gates of the perfect, sinless heaven.
Secondly, if you made the decision at any point in your life that you did not want anything to do with God for whatever reason, or just ignored Him altogether, why would you want to spend eternity in His presence? The Bible only says that Hell is "separation from God." All the stuff about burning, torture and the like is a warning of what people in that existance suffer emotionally and metally. They're not "burned alive" (for lack of a better term) they're just distraut with the realization that they have been cut off from God's influence out of their own volition.