Here's a theological argument for the intrinsic evil of lying:
- God can do anything which it is not intrinsically evil for a human person to do.
- God cannot lie. (Titus 1:2)
- Therefore, it is intrinsically evil for a human person to lie.
(1) is true because the omnipotence of God extends to every metaphysically possible thing which is not contrary to His nature. And anything it is permissible for a creature to do is something that is not contrary to the nature of God (if it were, it wouldn't be permissible for that creature). So if lying weren't intrinsically evil for human persons to do, then God could lie.
Of course, the converse of (1) is false: God can do some things it is intrinsically evil for a human person to do, such as to kill those who are innocent of violating human law.
