Some people are valued for their intellect. Claude Shannon was the finest mathematical engineer of his generation. Gleason Archer knew about 30 languages.
They shared something else in common: both became senile in old age. Even if it's understandable why God doesn't protect unbelievers from senility, why does he allow believers like Gleason Archer, John Sailhamer, and Elizabeth Elliot to be ravaged by dementia?
If you're valued for your mind, and you begin to lose your mind, what's left? Will you be discarded?
Elizabeth Elliot was a great Christian communicator, but when she began to lose her faculties, she didn't cease to be loved. She was treasured in her decline.
The tragedy of senile dementia is an opportunity to demonstrate the difference between Christianity and atheism. In a Christian family, a mother or father who's a shell of their former self is still cherished.
By contrast, euthanasia goes hand-in-hand with secularization: