You don't necessarily need to be religious to have a belief in the afterlife, or at least a strong enough suspicion of it to want to be respectful. As an analog

You don't necessarily need to be religious to have a belief in the afterlife, or at least a strong enough suspicion of it to want to be respectful. As an analogy, there's some evidence that people form memories when in a coma. Even if you can never prove that an individual is aware of you, it is still compassionate to assume that they can hear what you say about them.