“NEW LIFE IN CHRIST” or “NEW LIFE THROUGH CHRIST” means “an entirely different and new type of life, made possible by the Spirit of Christ (or of God) which one receives when one is saved” (cons. Rom. 8:3-4; Eph. 1:13-14).
The term new life in Christ is as compared to the life one was living before salvation or coming to Christ.
As soon as the Spirit of Christ comes into the man, the spirit and heart (or mind) of the man becomes recreated, or renewed, or regenerated (Ezk. 36:26; Col. 3:9-10; Tit. 3:5). This is when the spirit of the inner-man is called ‘a new man’ (2Cor. 5:17; Gal. 6:15; Eph. 4:24). The Spirit of God in the man now continually influences the man to live a spiritual life removing the carnal life.