Soul sleep is the idea that after a person dies, they exist unconsciously until the future resurrection. But is this idea taught in the Bible? I say no. I believe that after a person dies, if they have believed in Jesus for eternal life, they go immediately to be with God in heaven.
Many wonder what heaven will be like. It will be like Susan Boyle getting to do what she was made for. It will be like life, but without the pain and death. Heaven is not about sitting on clouds playing harps. It will be like this life, but without the pain, regret, and fear. Life will be what it was always meant to be.
Revelation 3:5 says that those who overcome will not be blotted out of the book of life. So if we do not overcome, we will get blotted out? No! Revelation 3:5 is using a figure of speech called litotes where a positive truth is stated in a negative way for emphasis. This post explains more detail about this figure of speech, how we often use it today in our own conversations, and how it helps us understand what Jesus is saying in Revelation 3:5.