Do you believe as annalex appears to that only Catholics have morals and only understand them after the Priest tells them what they are?
Annalex does not believe that, and I don’t think my posts even appear to say so.
There is one single moral law for all, whose source is God. Very many people have a good idea what the moral law is, and they follow it. Many non-Chrisitans have better morals than Christians, and many non-Catholics have better morals than Catholics. That is because moral law is natural law, it is, as St. Paul said, written in the hearts of all men (Rm 2:15).
You asked how one is sure in applying the law to oneself, and I answered that the best way is to ask the Church that Christ sent down with that very purpose in mind (Mt. 18:15-18).
Word the question reasonably and I’ll answer.