If you don't have a relationship with the only true God, creator of everything, you really have nothing. If you don't have the relationship described by Jesus in John 17:3
"This is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent."
This is not the "know of" we used to describe distant characters or people. This is a "know" like I know my wife. I know what see is all about, dislikes and likes, we communicate feelings and dreams with each other. If someone wrote a long letter to me I would be able to tell you if she wrote it or not by how things are written. I know the things she says, her desires, her humor...I could tell you if she would express things that way or not. To know God this way only comes through the saving power of Jesus. Our sinful state of being separates us from the perfect Holy living God. But he loves us so much He made a way that we can be clean and changed through His only Son Jesus. Now we can have that close relationship.
If you don't have this relationship, then you don't have anything. If you don't have this relationship with God you have a false sense of security in the things around you. Your things..house, money, relationships, retirement plan, job can all be gone tomorrow. Even the things you take for granted...your family, friends, health, ability to think or reason can all be gone in a moments notice. The only thing that has and ever will remain or mean something is your state with the living God. If you just "know of Him" there is still something between you and Him. If you "know Him" you have everything that will last for eternity.
For most people this life in creation with all it's beauty and pain is as close to Heaven as they will ever get. For true Christians who have entered in to a relationship through the saving Grace of Jesus...this as close to Hell as they will ever get.