The fear of death is the most primal, pure kind of fear. Humans, as a general rule, don't like what they don't understand, and death itself is a concept that we're not able to fully grasp, let alone comprehend. We like to think there's something after our life, some trascendental purpose that gives death a more gentle, sweet scent, rather than put it as the abrup, dark end that (I think) it is. There's where the spirit comes into; our belief that some kind of soul of us carries on after we're gone.
I see that belief as a fabrication created out of fear of death. I think that once you die, that's it. That's the end. Your consciousness simply fades away, and you cease to exist. There's no soul or spirit that goes on. There's nothing.
You can disagree all you want, but it's not a dumb statement, sir. It's my opinion.
But your family, your friends and relatives, memories people have of you, what you achieved, the way you affected the world around you, your output and the things you left behind, that's your spirit. In the same way you could say your spirit is in the things influenced by your existence, whether you're alive or dead.
So you never really die, and if you say there's "nothing" after death, you've been looking at your own existence from a wrong perspective. The existence of any person is not defined by them alone. You are a part of other people, and other people are a part of you.