[Quietism] asserts that the Christian is to be passive (quiet) in the process of spiritual growth and let God do everything. According to quietist teaching, the Christian must exert no energy or effort in the process whatsoever, for feeble human effort only hinders the working of God’s power. Quietists believe Christians must simply surrender fully to the Holy Spirit (also called “yielding,” “dying to self,” “crucifying oneself,” “mortifying the flesh,” or “placing one’s life on the altar”). The Spirit then moves in and lives a life of victory through us, and Christ literally replaces us (“it is no longer I who lives, but Christ lives in me” – Gal. 2:20). In its extreme variety, quietism is a spiritual passivism in which God becomes wholly responsible for the believer’s behavior, and the believer feels he must never exert personal effort to pursue righteous living. Quietists have popularized the phrases, “Let go and let God,” and “I can’t; He can.”
John MacArthur