What is "sound doctrine"?
Matthew 13:52 Treasures New and Old. 51 “Do you understand all these things?” They answered, “Yes.” 52 And he replied, “Then every scribe who has been instructed in the kingdom of heaven is like the head of a household who brings from his storeroom both the new and the old.” 53 When Jesus finished these parables, he went away from there
A closet
A storeroom is sort of like a closet. A place where people keep all sorts of stuff that they want or need. Some of it is new, like my new boots that I’ve been wanting to wear, but its been too wet and I don’t want to get them messed up.
And then, there’s the old stuff. I know there are jackets in my closet that I probably can’t wear anymore. Come to think of it, it's almost time for Spring cleaning.
The Church
Well, the Catholic Church is where Christ has put His Deposit of Faith. And this Deposit of Faith consists of New Stuff. Like the story of His life, death and resurrection. And His proverbs. And the Beatitudes and Sacraments.
Then, there’s the Old Stuff, like the Old Testament Scriptures, the Ten Commandments, and the history of salvation.
A Teacher
And Jesus Christ established a Teacher, a Scribe, who can infallibly bring forth from His storeroom, the Old and the New. The Magisterium.
Does that make sense?