The phrase “mere Christianity” was popularized from the title of C.S. Lewis’ book published in 1952. Christianity Today placed Lewis’ Mere Christianity third on the list of most influential books since 1945. Famous physician-geneticist and author Francis Collins and popular Christian author Charles Colson are two among many others who point to this influential book as the starting point to their Christian faith. Even Grammy award winning band Sixpence None the Richer is named from a phrase out of Mere Christianity.  

So why has this book had such a significant impact on so many people from various backgrounds and beliefs? Lewis stresses in his book that his desire is for his unbelieving neighbor to come into the Christian fold, not to convince him or her of his own theological positions.  He says in the preface, “But in this book I am not trying to convert anyone to my own position. Ever since I became a Christian I have thought that the best, perhaps the only, service I could do for my unbelieving neighbours was to explain and defend the belief that has been common to nearly ALL Christians at ALL times.”  

So what exactly does it look like to defend “mere Christianity?”  I think what one has to do is identify what exactly are the essential beliefs for becoming a Christian, and then defend those essentials.  When an issue gets brought up by the unbeliever that is not an essential, recognize its secondary nature, and use wisdom and caution if deciding to answer.  Lewis cautions people in disputing questions that divide Christians with unbelievers as he says, “I think we must admit that the discussion of these disputed points has no tendency at all to bring an outsider into the Christian fold.”  

So what are the essential beliefs one must hold to become a Christian?  The answer to this question has been disputed by many, and I have found my list to be quite short.  Before I state my feelings on the essentials, I want to be clear that just because one gives intellectual accent to these core beliefs, that alone does not make a person a Christian.  However, holding these key beliefs is the starting point for coming into a saving relationship with Jesus Christ.  The first belief one must hold is that God exists as the first cause or creator of the universe and is the source of moral goodness. They would also need to believe that the person of Jesus of Nazareth existed; that Jesus claimed to be God; and that He came to this earth, died, and then God rose Him physically from the dead in vindication of His claim.  Now if these two statements are true (God exists as creator and source of moral goodness and Jesus rose from the dead) then Christianity at its core is true, and the most reasonable thing for a person to do is become a Christian. In taking the next steps a person would also have to recognize that they are a sinner (they miss the mark) of God’s perfect standard and are therefore in need of saving. Finally, a person would have to believe that it was Jesus’ sacrifice that pays the debt caused by our sin.  Acceptance of these beliefs sets the stage for a person to enter into the saving relationship with Christ.

By identifying the essentials it then becomes clear to see how many nonessential beliefs there are when discussing with the skeptical unbeliever.  One common nonessential is Darwinian evolution.  I have heard of numerous accounts of Christians claiming to “loose their faith” because they are no longer satisfied with a literal account of creation as described in Genesis.  If Darwinian evolution is true, it does not logically follow that the Christian God does not exist.  What would follow is that if Darwinian evolution is true, the early chapters of Genesis are either false or not intended to be taken literally.  The latter of these explanations is a topic that has been of great debate among Christian scholars.  Christians such as Francis Collins (geneticist who was mentioned earlier) identifies himself as a theistic evolutionist while someone like Ken Ham (from Answers in Genesis) takes a more literal approach to the early chapters of Genesis.  Christian philosopher and apologist William Lane Craig made these remarks when responding to a student who claimed agnosticism because she accepted Darwin’s Theory of Evolution.  “The Christian worldview can be thought of as a web of beliefs, rather like a spider’s web, with core doctrines represented by the innermost strands of the web and less important doctrines represented by the strands radiating from the web’s core to its periphery. Changes in core doctrines will result in great reverberations throughout the web, whereas changes in less central doctrines will require adjustments to the web but will not destroy the entire structure.”  The point is that Christians are free to follow the evidence where it leads in this regard, and wherever one lands on this issue, the truth of Christianity is not threatened.  

Other nonessentials that I often hear skeptics address are biblical inerrancy and inspiration of the scriptures.  Both of these topics are important and worthy of discussion, however one can accept the core teachings of Christianity and have different beliefs on this matter.  Many people would be surprised by some of C.S. Lewis’ views on these two issues.  In 1959 Lewis remarked in a letter to Clyde Kilby who chaired the English Department at Wheaton College, “Errors of minor fact are permitted to remain” in Scripture, he wrote. “One must remember of course that our modern and western attention to dates, numbers, etc. simply did not exist in the ancient world. No one was looking for that sort of truth” (Letters, vol. 3, 961, emphasis original). For more information on Lewis’ views on both inerrancy and inspiration of scriptures you can click here.  

As a follower of Jesus I want to be a defender of “mere Christianity.”  I think it is beneficial for Christians to study, think hard, and discuss with other believers these important but nonessential issues.  Through practicing disciplined thinking on these topics we will no doubt grow in our knowledge of God.  I feel we should take positions following our study and disciplined thinking, and at appropriate times share these positions in a respectful and humble manner.  However, I believe we should never forget that our defense always begins with “mere Christianity.”  To conclude it was Lewis who said,  “For I was not writing to expound something I could call 'my religion,' but to expound 'mere' Christianity, which is what it is and was what it was long before I was born and whether I like it or not.”