Why is trusting in Christ alone important for Christian sanctification?

In Galatians 3:3, Paul challenges the notion that believers can achieve sanctification through their own efforts by asking, 'Are you so foolish? Having begun in the Spirit, are you now made perfect by the flesh?' This question emphasizes that all aspects of a Christian's walk, including sanctification, depend entirely on the work of the Holy Spirit through faith in Christ. The believer's pursuit of holiness is not achieved through adhering to the law, but instead through reliance on the Spirit who produces true righteousness within them. This crucial truth frees believers from the burden of legalism and points them towards the transformative power of Christ's redeeming work.