What does it mean to not conform to the pattern of this world (Romans 12:2)?

from the old testament

• God continually told His people, Israel, to separate themselves from the sinful, idolatrous tribes around them; He told them to faithfully follow His laws and not allow pagan practices to entice and mold them. Isaiah 52:11 is referenced in 2 Corinthians 6:17 where it says, “Therefore, come out from among them and be separate, says the Lord; do not touch any unclean thing, and I will welcome you” (CSB). The clause come out from among them is from Isaiah 52:11. Paul is taking familiar wording and giving it meaning in a fresh context. Just as the Israelites in exile were to put off any idolatry they may have picked up while living in Egypt, so the Corinthian believers are to lay aside the idolatry and sexual immorality that they were steeped in by virtue of living in Corinth. They must be separate from the sin of the world. This applies to all believers.

from the new testament

• Second Corinthians 5:17 says that "if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come." When we put our faith in Jesus, we are forgiven of our sin and we're also made new.
• We study God's Word so we can better know Him and be better established in truth (Psalm 1:1–4; 2 Timothy 3:16–17; Hebrews 4:12–13; 5:14).
• We yield to the work of the Holy Spirit in our hearts (Philippians 2:12–13).
• We seek to abide in Christ and obey Him (John 15:1–11).
• We "put off the old” creation and "put on the new" (Colossians 3:1–17), not walking according to the futile ways of the world but instead living in the ways of “the new self, created after the likeness of God in true righteousness and holiness” (Ephesians 4:17–32).
• We spend time with other believers for encouragement, equipping, accountability, and support (Hebrews 10:24–25; Galatians 6:1–10).
• We actively use our spiritual gifts for the benefit of others (Romans 12:3–8).
• We seek to live at peace with others (Romans 12:18), having a humble heart that is willing to serve even our enemies (Romans 12:19–21; Philippians 2:1–11).

implications for today

There is more difficulty in not conforming to the pattern of this world than we realize. How are we to keep from being conformed to the sinful world system, especially considering our own sinful tendencies (James 1:12–18; Romans 7—8)? How do we remain "in the world yet not be of the world" (cf. John 17:15–18)? How can we genuinely love the people around us, including those who are of the world, without accepting a worldly way of thinking? Paul gives us the answer: "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" (Romans 12:2).

When we abide in Christ (John 15), our will becomes conformed to His will. Our desires are shaped by His. What we live for and how we live are shaped by Him. Paul gives an example of what those who are conformed to His image are called to do: "Let love be genuine. Abhor what is evil; hold fast to what is good. Love one another with brotherly affection. Outdo one another in showing honor. Do not be slothful in zeal, be fervent in spirit, serve the Lord. Rejoice in hope, be patient in tribulation, be constant in prayer. Contribute to the needs of the saints and seek to show hospitality. Bless those who persecute you; bless and do not curse them" (Romans 12:9–14). This is how Christians are supposed to live. Being conformed to Christ ultimately looks like loving God and loving others with His agape love—a love that genuinely seeks the good of the other and is willing to sacrifice oneself (Romans 13:8; John 13:34–35). Ephesians 5:1–2 tells us, "Be imitators of God, as beloved children. And walk in love, as Christ loved us and gave himself up for us, a fragrant offering and sacrifice to God." If we are conformed to Christ, we cannot, and we will not be conformed to the world.