What does the phrase 'the faithful in Christ Jesus' mean?

'The faithful in Christ Jesus' signifies a distinct group of individuals identified by their faith in Christ. In Ephesians 1:1, Paul addresses the church at Ephesus as 'the saints, which are at Ephesus, and to the faithful in Christ Jesus.' This implies that the letter is directed towards believers, those who have been sanctified by God and granted faith through His grace. They are recognized as faithful because their faith rests in Christ, showcasing God's action of choosing and sustaining belief among His people.