Death is a perennial issue for humanity. It is not surprising, then, that the book WHAT LUTHER SAYS, has 25 pages of quotes from Martin Luther on the subject (363-388). What follows is the first quote on the topic, which is the 1065th quote in the book.
IN THE DAYS of Martin Luther, too, there were people who for various reasons pictured death as something natural. But the Reformer was not one of them. This appears from his interpretation of 1 Cor. 15:22 (October 20, 1532).
1065 Death Is Decidedly Unnatural The heart and wisdom of no man have hit upon the idea that death is the penalty for sin, but all men have thought and held that it is our natural lot (ein natürlich Anfall), just as a dog or a pig or any other animal dies or as the sun rises and sets, grass grows and withers, and all things are perishable by nature and pass away as they have come. But Scripture teaches us that our death does not come about in a natural way, but that it is a fruit of, and a punishment for, the sin of our father Adam, who so flagrantly violated the exalted Majesty that he and all his descendants who are born on earth must be the prey of death forever; and no one on earth can escape or prevent this clamity. (W 36, 557 – E 51, 148 f – SL 8, 1157)
Plass, Ewald M WHAT LUTHER SAYS: A Practical In-Home Anthology for the Active Christian 363