Why is the Doctrine of Hell important?

Tim Keller, of Redeemer Presbyterian Church in New York City, tells us about The Importance of Hell:
1. It is important because Jesus taught about it more than all other Biblical authors put together.
2. It is important because it shows how infinitely dependent we are on God for everything.
3. It is important because it unveils the seriousness and danger of living life for yourself.
4. The doctrine of hell is important because it is the only way to know how much Jesus loved us and how much he did for us.