“Let your mind be renewed” (Romans 12:1-2). Is that a command to pray for renewal (law, second commandment), a command to diligently hear and learn the word of God (law, third commandment), or an invitation to believe the promise of forgiveness (gospel)?

As Anders Nygren pointed out in his commentary, Paul had just proclaimed the good news that “he who through faith is righteous shall live” (Romans 1) in freedom from wrath (Romans 5), sin (Romans 6), the law (Romans 7), and death (Romans 8) in agreement with God’s promise to Abraham (Romans 9-11). Thus, Romans 12:1-2 invites the audience to be renewed by believing that good news.  The good works of the remainder of the book result from that renewal of the mind.