Obedience
In an attempt to provide a counter-example to someone (you know who you are) I give the barest bones argument on obedience as it occurred to me.
1 God exists? a: yes b: noif b forget the whole thing, if a continue
2 God has a will? a: yes b: no
if b go back to 1 and re-examine, if a continue
3 Follow God's will? a: yes b: no
if b go back to 1 and re-evaluate, if a continue
4 Follow God's will either: a per se or b: per accidens
if b then 3a or 3b equally valid, if a then obedience.
Thus obedience as a virtue requires God exists, He has a will, one follows God's will and that is intentional. Therefore there is some sense in which God's will must be knowable. But this can be known in two ways: the indelible stamp of natural law on men's hearts, and also in terms of the moral law that does not pertain to natural law. Therefore, we continue:
5 God's law is knowable: a Institutionally or b: privately
but if b then either back to 4b which rejects obedience, or private personal revelation to everyone, which contradicts natural experience. Therefore, if 5a then there is an institution of God (church). Therefore:
6 The institution of God is: a: visible b: invisible
But if 6b then back to 5b.
Therefore, if there is a God, with a will, that is to be followed in itself, there must be a knowable moral law institutionally in a visible church. This, according to the brief argument I have inadequately lain out, is obedience.