The spirit world and the physical world are different, but they intertwine here this universe. We are spiritual beings in that we believe in a higher power, gravitate to non physical things (music, philosophy, etc). But the physical side of us tends to overtake our spirit because we fear pain, death, boredom and anything that threatens our physical being. We don't know too much of the spirit world, because it's not talked about often. But death is certain in this existence, we see it everyday. That concept alone should have put things in perspective a long time ago for some of us, but we still live in confusion, killing ourselves and each other for things that aren't gonna matter years from now. The US dollar is deteriorating, natural resources are being depleted, kingdoms and governments collapse, culture changes... everything gets replaced in this world. But the fact that we exist never does. We are just energy channeled via these bodies. Of course, realizing this would drive some people to suicide and worse. That's why it's on us to make the decisions to live to the best of OUR abilites, and not by religions that help create these problems that leave us confused in the first place.
And to those who don't think eternity exists, where do you think the word comes from? Something that doesn't exist can't be spoken, dreamt or even thought about, especially a complex concept such as something that goes on forever.