"Mere Christianity and Moral Christianity" defends the biblical doctrine of unconditional security by demonstrating that perseverance in faith cannot be made a condition for reaching heaven without teaching salvation by works. An extended prologue and introduction prepare the reader for the more advanced material in the body of the book by sharing personal examples regarding the urgent need of such a book to counteract the prevalent legalism typically encountered within the church and within popular evangelism. The first chapter interacts with C. S. Lewis. Positive interaction with his philosophical defense of Christianity and Jesus' Deity is followed by critical discussion of his Arminian views regarding conditional security. The second chapter explores a related Reformed perspective from Jonathan Edwards. A parallel perspective within Catholicism regarding merit by Thomas Aquinas is explained. The third chapter interacts with contemporary Arminian and Calvinistic authors. Appendix one shows that the ordo apostasia that would be necessary for the loss of the gift of eternal life is biblically impossible. The objection that moral performance is merely necessary evidence rather than a condition for the retention of eternal life is evaluated and rejected in appendix two. Appendix three demonstrates that moral repentance necessarily entails merit and therefore cannot be a condition for entrance into heaven. Appendix four locates moral repentance within the gospel of the kingdom, which is a substratum of the gospel of Jesus. The gospel of grace, which is the aspect upon which one's security from eternal damnation is solely conditioned, does not contain a call for repentance as a theological condition for such salvation. Benefits of this book to the reader include providing a solid foundation for understanding how performance-related concepts such as repentance, commitment, and perseverance can play a positive role without being made a legalistic distraction.