- Deontology is true.
- A finite being could not have the kind of dignity that deontology ascribes to human beings.
- So, human beings are infinite. (1-2)
- If human beings are infinite, they are infinite synchronically or diachronically.
- If naturalism is true, human beings are finite synchronically.
- If there is no infinite afterlife, human beings are finite diachronically.
- So, either naturalism is not true or there is an infinite afterlife. (3-6)
- So, if naturalism is true, there is an infinite afterlife. (this is a material conditional following from 7)
Of course, there are also arguments that if naturalism is true, there is no afterlife, and if these are sound, then together we get an argument that naturalism is not true.