What does the Bible say about reformation vs regeneration?

Scripture clearly differentiates between reformation and regeneration. In 2 Kings, Jehoram exhibits a form of reformation by discontinuing some of his predecessors' sinful practices, yet he still engages in evil before the Lord. This illustrates that mere outward change, often associated with reformation, does not indicate an inward heart change or true conversion, which comes only through regeneration by the Holy Spirit. Jesus emphasized this in the New Testament, declaring that a clean heart must also be filled with the Spirit — otherwise, it remains vulnerable to returning to old sins. Thus, while reformation may make one appear 'better' to others, it is regeneration that brings true life and salvation.