Do you believe that when you die, you're going to rot? That this world is all you have? That one day the sun is going to burn out and civilization is going to be gone and nobody will remember anything anybody's ever done? Or do you believe what John writes about in Revelation 21:
"He will wipe every tear from their eyes, and there will be no more death or sorrow or crying or pain. All things are gone forever. And the one sitting on the throne said 'Look, I am making everything new!'"
When you study the narrative of the Bible from Genesis to Revelation, the central theme of scripture is Restoration. When sin entered the world, the perfection and paradise God had established for His people was shattered. We see all throughout scripture God's plan to restore His people--to undo the curse of sin. When you understand God's design to restore, it produces a hope for you that can't be found anywhere else in the world.
It's not an abstract idea. It's a real, living, certain hope.
What we believe about the future determines how we respond in the present.