Christ implies that Honesty with self and others is required to properly receive the third truth…This includes the sacrament of Confession. Confession can only be administrated by a good standing Catholic Priest.
John 20:21-23 He said therefore to them again: Peace be to you. When he had said this, he breathed on them; and he said to them: Receive ye the Holy Ghost. Whose sins you shall forgive, they are forgiven them; and whose sins you shall retain, they are retained.
— Douay-Rheims Version