Ques. Does the word "Church" always mean the same people?
Ans. The word "Church" means "assembly." It has two distinct aspects. The one is called the "House of God which is the Church of the living God, the pillar and ground of the truth" (1 Tim. 3:15).
The other is "the Church which is His body," the fullness of Him who filleth all in all. The first is put into man's responsibility, so failure and corruption have come into it (1 Cor. 3:10-17; Eph. 4:5; 1 Peter 4:17, and many other passages).
The second depends on God, and is built by the Holy Spirit, so none but saved ones are in it. Such verses as Matt. 16:18; 1 Cor. 12:12, 13; Rom. 12:4, 5; Eph. 4:4; 5:25, apply to it. All who are saved shall be caught up to be forever with the Lord (1 Thess. 4:15-16). All who are only professors, without the new life, shall be left behind, forever lost.