When the New Testament addresses spiritual maturity, it uses the common Greek word teleios
, which means “perfect” or “complete.” When it is applied to Christian growth, it indicates spiritual maturity in contrast to childlike immaturity as, for example, in this command from Paul: “Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature (teleioi).” (1 Cor. 14:20; see also Heb.5:13–6:1). Sometimes it indicates perfection, as in Jesus’ summary command in the Sermon on the Mount: “You therefore must be perfect, as your heavenly father is perfect” (Matt.5:48). Spiritually, it always references solid, biblically informed understanding and conduct in Christ—spiritual adulthood.