The central message of this sermon is that living the Christian life involves a constant battle between the flesh (fallen human nature) and the Spirit, but ultimately, it's not an equal or 50/50 struggle. As Christians, we have been born again, made new in Christ, and are no longer defined by our old sinful nature. The flesh is like a disease that needs to be managed, and it will always try to exert its influence, but when we live by the Spirit, we can resist its desires and remain true to our identity as children of God. This sermon emphasizes the crucial distinction between being a Christian and living like one, suggesting that many people who claim to follow Christ are actually allowing their fleshly nature to dominate their lives. The takeaway is that genuine Christianity involves not just intellectual assent or ritual observance, but a transformation of the heart and mind, where we acknowledge our ongoing struggle with sin, but also recognize our new identity in Christ and live accordingly.