The written word will outlive us all. Your generations will know your work for Jesus. Perhaps even get saved due to your work. While some will go up in the rapture and the books will remain behind, still guiding others. As God has called you to write this book, this may help lead the way by giving you the basics. Take the Bible for example. While our work cannot be compared with this great book, we hope many will be touched in their hearts to serve and be saved by the Master who had many write about Him, and are still writing books. We base this upon the scripture in the Book of John 21:25:
And there are also many other things that Jesus did, which if they were written one by one, I suppose that even the world itself could not contain the books that would be written. Amen.