The central message of this sermon is that salvation is the work of God, not dependent on human effort or behavior, and that believers are secure in Christ due to God's eternal plan and purpose. This idea advances the belief in predestination, where God's sovereignty and determinative choice guarantee the salvation of those He has chosen. The takeaway is that while humans have free will and can make choices, ultimately, God's work in salvation ensures that none will be lost or separated from Him, and believers are called to "work out their salvation" not through their own effort, but by trusting in God's ongoing work in them.