A proposition that cannot be carried into practice at all cannot be true. An act that cannot be implemented in actuality must be somehow incoherent: self-refuting – for example, you can’t mean it when you say, “this statement is a lie” – or a contradiction in terms either simple or implicit – e.g., there’s just no way to implement “2 + 3 = 4,” for it is a contradiction in terms. That such propositions can’t work logically means that they can’t work in practice.
But a proposition that can be carried into practice might be true. E.g., “It is best not to defer gratification.”
When we sin, we assert one or more of a number of propositions:
- God does not exist.
- God is not omniscient.
- God is amoral.
- The world is amoral.
- God does not care whether I behave well or not, nor does the world.
- Whether or not God cares about my behavior does not matter (to me, at least).
And so forth. When we misbehave, we effectually attest to our belief in at least one of these propositions, or else in one of a number of other propositions like them. And to attest belief in propositions is to testify to their truth, and so is to urge their truth: behavior is an effectual proposal for how it might be well to behave.