I taught a class on this book a few years ago.
Here are some of my notes:
4:13 Old Testament believers had an imperfect and incomplete knowledge of what happened to a person at the time of death. To them sheol was an all-purpose word used to describe the disembodied state, both of believers and unbelievers.
They believed that everyone would die eventually, that apparently there would be one general resurrection at the end of the world, and then a final judgment. Martha reflected these sketchy views when she said,