Romans 12:2 — "Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect." Greek anakainōsis tou noos: anakainōsis is "making new again, renovation" — the same word used of the Spirit's regenerating work (Titus 3:5); nous is "mind, understanding, inner perception." The verb for transformation is metamorphoō — metamorphosis, the same word used of Jesus' transfiguration.
Sanctification happens in the mind first. What you believe controls what you do; what you habitually think you will eventually become. Every day, millions of messages from a fallen culture aim to conform your mind to its pattern — defining beauty, success, sexuality, identity, purpose, hope, despair, truth, and meaning according to a script written by the world. Paul's command is a counter-program: be transformed by the renewal of your mind. The renewal comes through steady input of God's Word (it is Scripture that washes the mind, Ephesians 5:26), through preaching (Romans 10:17 — "faith comes by hearing"), through meditation, through fellowship with renewed-mind Christians, through the Spirit's direct work. Over time, your categories shift — what once looked attractive now looks hollow, what once seemed strange now feels like home, what once terrified no longer moves you. The renewal is slow but real. The alternative — not engaging in renewal — is conformity by default, because the world catechizes you 24/7. Turn off the world's feed and open the Word. Your mind will follow.