I can say some god talked to me and told me to kill everybody...does that mean it's true? No. I might believe it because the mind likes playing tricks on us, but that's all it is.
If you want the logical and scientific explanation, nothing. We die and our life is over. Our brain shuts down and our body decomposes. Memories are a product of the brain made through essentially a ton of luck and many many years of evolution. We are no different than the tiger who dies or the dog who dies or the ant that dies. We are animals. We are a collection of an unfathomable amount of cells made of atoms put together in a miraculous way that took billions of years to design. When we die, our those cells die and those atoms break apart. Our brain is no longer working. We just cease to exist. That is all. Nothingness. No feeling or knowledge of existence. No actions. No anything. We no longer exist. Our life is over.
This is all rather gloomy though, so what many people choose to do is pick a book of fables and 1 or more unknown all-powerful imaginary friends and believe in that. It gives you an answer to these questions that isn't so...unknown...and out of our control.
Personally I'm an atheist, but I understand why we need religion. Life is full of unknowns, and religion gives us the answers. Is it real? No. Does it help some people get through to the next day? Of course.
Many people can't fathom or understand living a life with no meaning. Religion gives you that meaning, although it is just a facade. If you ask me, life is about living. Spending our time alive wisely. Being happy. Living. Once it's over, all that's left is your legacy with the people you left behind. Once your life is over, it's over. For that reason we should live in the moment.