"Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both theirs and ours." (1 Corinthians 1:2)
This salutation to those "called saints" at Corinth (the words "to be" are not in the original) makes it clear that all who "in every place call upon the name of Jesus Christ our Lord" are the saints of God. The word "saint" means "one who is sanctified" or "set apart," having been called to serve the Lord.
That service is varied, and many striking figures of speech are used in the Bible to describe it. In the first place, the saints are "witnesses unto me" (Acts 1:8) and, therefore, "ambassadors for Christ" (2 Corinthians 5:20). The words and deeds of believers are to serve as an actual Bible to those who may not read God's Word. "Forasmuch as ye are manifestly declared to be the epistle of Christ ministered by us, written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart" (2 Corinthians 3:3).
Christ applied the figure of candlesticks to the churches addressed in Revelation, with Himself in the midst (Revelation 1:12-13). Similarly, we are enjoined to "shine as lights in the world; Holding forth the word of life" (Philippians 2:15-16). This light is not merely the light of a godly life, but the light of God's revealed truth, for we constitute "the church of the living God, the pillar and ground of the truth" (1 Timothy 3:15).
In relation to Christ, we constitute "the body of Christ, and members in particular" (1 Corinthians 12:27) and have been presented "as a chaste virgin to Christ" (2 Corinthians 11:2). One day we shall reign with Him as "kings and priests unto God" (Revelation 1:6). HMM