Saints and faithful
According to the pattern of two, saints would refer to those in the visible church in Ephesus, and faithful would refer to those in the invisible church. This will become apparent when he answers the question of "How then should we live"?" he gives instructions to put away certain practices. They were still living in the flesh, as we all do, still having the goat nature. The visible church is filled with people of the flesh.
The faithful also refers to the same people being the sheep. In the spirit they choose to live by the word of God rather than by the instinctive goat.
His appeal will instruct the goat and commend the sheep.
He addresses the saints, or goats in the physical location of Ephesus. He speaks to the faithful in the spiritual reality of being 'in Christ'. He uses 'Christ Jesus' since 'Christ', the messiah (the spiritual), is the focus of the title.
