As a designation of Christians, means full of faith, trustful, and not simply trustworthy (Acts 10:45; 16:1; 2 Cor. 6:15; Col. 1:2; 1 Tim. 4:3, 12; 5:16; 6:2; Titus 1:6; Eph. 1:1; 1 Cor. 4:17, etc.).
It is used also of God's word or covenant as true and to be trusted (Ps. 119:86, 138; Isa. 25:1; 1 Tim. 1:15; Rev. 21:5; 22:6, etc.).