Why is the subject of hell important? There are only two destinies of every human after we die. There is no middle ground. If you are saved (which means your hope of heaven is the blood of Christ), you will go to heaven when you die. If you are lost (which means you did not trust Jesus' death on the cross for your salvation), you will go to hell.
I wish it weren't so. If God left it up to me, I would save everybody. I'd let everyone into heaven. Mind you, God could have opted for this; He is God, after all, and can do anything He wants. But for reasons I do not understand, God created hell and has determined that all who do not affirm His Son's death on the cross will go there. In other words, hell is God's idea—not mine.
There are many doctrines in Scripture I don't understand. I could give a long list that includes the Trinity, why God created humankind knowing we would suffer, and why there is so much injustice in the world He created—which He does not (for some reason) stop. Does this make me stop preaching, all because I don't have these questions answered? No. An ambassador may not understand all he is defending. Likewise, as God's ambassador I don't always understand all I am called to preach. But I defend it because I believe in God's Word. This is why I believe in—and preach—hell.
Still, the question emerges: Does the Bible really teach that there is a heaven and a hell, and that only the saved go to heaven? For nearly 2,000 years the church thought this is what the Bible taught. But we have become too "enlightened" for this ancient belief. We reason that either God is too merciful to send people to hell or that hell does not exist. To back our brazen departure from Christian orthodoxy, we teach annihilation (that unbelievers will be obliterated) or universalism (that all will be saved). What was once either "liberal" theology or cultish teaching has now become virtually mainstream in contemporary Christianity.
A person without any theological or philosophical prejudice may not believe in hell but would certainly believe that the Bible teaches the possibility of two destinies: heaven or hell.
If there is no hell, there is no heaven. The two rise or fall together. You and I have no right whatever to believe people will go to heaven except by virtue of God's Word. The same Bible that teaches heaven also teaches hell.
I believe in heaven. I thank God I am going there. I can claim no merit in myself that I am going to heaven. It is by the sheer grace of God I am going to heaven. God did it all. I am not worthy of it. I will never understand why God saved me. But He did. It is equally true that all who want to go to heaven can. And all who want to avoid hell can. Jesus died for everybody. John 3:16 reminds us that "whoever believes in Him [Jesus] shall not perish."
The question is, do you believe it? Do you preach it?