This (2 Cor 5) sounds more like a sermon for the marketplace rather than for the local church in Corinth. Yet Paul is preaching to Christians. It is as if he were saying to them: “What you need to hear most of all is the gospel, and the gospel that you need to hear is the same gospel I preached out there in the marketplace.” He understands that our greatest need, whether we are Christians or not, is to respond to the gospel. So whether he is speaking to non-Christians or to Christians, he is unashamed to say to them, “Understand this, respond to God’s saving grace in Christ, and life will be transformed.”
~ Sinclair Ferguson By Grace Alone, 51.
If you are looking for a book that will cause you to rejoice in God’s grace to us in Jesus Christ, then read this book by Ferguson. It is glorious, because it is all about the gospel and God’s amazing grace. The chapter on security was particularly encouraging and helpful personally, as well as thinking about seeking to help others with this issue.