The central message of this sermon is that Christians are being transformed into the image of Christ through a process of metamorphosis, which involves a complete change from their old self to their new self in Christ. This transformation is not just about legal status or outward behavior, but about a deep and fundamental change in who they are as people. The speaker emphasizes that this process is not a one-time event, but a lifelong journey that continues until glorification, where the Christian will be completely conformed to the image of Christ. The takeaway is that Christians should understand their true identity in Christ, which is their position, and strive to live according to it, rather than being defined by their current condition or experience. This message advances the belief that Christianity is not just about behavior modification or moral improvement, but about a radical transformation that occurs as a result of being in Christ.