For anyone who takes the Christian faith seriously, the Bible remains the irreplaceable foundation of our lives. Scripture reveals to us what we must believe and how we must live. The Word of God, given to us across sixty-six books, contains every truth we need for salvation and for life in this world. Yet if we are honest with ourselves, reading the whole of Scripture and grasping the full depth of its meaning is no simple task — particularly in an age like ours, where rapid consumption has replaced sustained reflection as the highest virtue.
In times like these, keeping such illuminating works alongside Scripture is no small matter. Among the countless volumes of Christian literature available to us, the one I recommend above all others is C.S. Lewis's Mere Christianity. That this book, now more than seventy years old, has lost none of its vitality is no accident. It is because Lewis refused to chase the fashions of his moment and instead anchored himself to the unchanging substance of the Christian faith. Of all Lewis's works, this is the one to read first — for no other gives us so comprehensive and so balanced a view of the whole landscape of Christian belief.
What Do We Believe?
Mere Christianity is organized into four broad sections, three of which — Books One, Two, and Four — are devoted to the question of what Christians actually believe. Lewis begins by placing the reigning worldview of our age — moral relativism — in direct confrontation with Christian absolutism. This is no mere academic exercise. Just as Calvin declared at the outset of the Institutes that knowledge of God and knowledge of ourselves are bound together inseparably, Lewis argues with equal precision that the question of moral truth is ultimately inseparable from the question of God's existence.
Too many Christians today live out their faith without any clear sense of what they believe. They confess that they "believe in Jesus," yet have never seriously wrestled with who Jesus is, what His atoning work means, or what the doctrine of the Trinity actually teaches. But Christianity is not a religion of blind sentiment. God is rational. He has revealed Himself to us, and He desires that we know and believe that revelation clearly and intelligently. The Reformed tradition has always insisted that right doctrine is the foundation of right living — and Lewis, whether he would have claimed the label or not, writes in that same spirit.
At the close of Book Two, Lewis issues this urgent appeal to his readers:
"Now, today, this moment, is our chance to choose the right side. God is holding back to give us that chance. It will not last forever. We must take it or leave it."
This is not mere decisionism. It is a call to human responsibility in the face of God's sovereign invitation. From a Calvinist standpoint, we understand that even this response is made possible only by grace. Yet Lewis's words do not contradict that truth — they remind us that those who stand before revealed truth have no warrant for spiritual laziness or indifference.
How Then Shall We Live?
Had this book ended as a work of Christian apologetics, it would already deserve a place on every believer's shelf. But Lewis does not stop there. In Book Three, he presses further into the more urgent and practical question: how is the Christian actually to live?
Lewis begins with a discussion of morality in general, moves to a careful contrast between the world's ethical framework and the ethics of Christianity, and concludes by showing how Christian moral teaching connects to the concrete realities of daily life. The subjects he takes up — social morality, sexual ethics, marriage, love, hope, faith — read less like the concerns of 1952 and more like the front page of today's newspaper. This is precisely what we should expect from truth that transcends every age.
The passage that struck me most deeply is Lewis's definition of Christian love. Many of us excuse ourselves from practicing love by citing our temperament — we are introverted, we are reserved, we are not naturally warm people. Lewis flatly rejects this excuse. Christian love, he insists, is not a matter of feeling but of will. This is ground the Reformed tradition has long occupied. Our emotions remain under the influence of our fallen nature, but the will, renewed by God's grace, can choose to love even when feeling does not follow.
Lewis also brings welcome clarity to the relationship between works and salvation. We do not live rightly in order to earn our salvation. We live rightly because salvation has already begun in us — because we have already tasted, however faintly, the first light of heaven. This is the very heart of Reformed soteriology: sanctification is not the cause of justification but its fruit.
Why We Must Read Mere Christianity Now
We live in a moment of unprecedented information overload, where competing values and ideologies press in on us from every direction. Yet strip away the surface noise, and most of what our culture offers us rests on the same three foundations: materialism, emotivism, and self-centered individualism. The danger for the church is that we have absorbed these assumptions without noticing. We attend services, participate in community, and consider ourselves faithful — while quietly pursuing the same things the world pursues.
Mere Christianity makes us uncomfortable. And that discomfort is precisely its gift. Lewis dismantles our favorite excuses one by one, shows us exactly where we are standing, and points us — on the authority of Scripture — toward where we ought to be headed.
Reading this book is not the completion of faith. But it is a profoundly clarifying mirror, one that shows us both what we believe and how we are called to live in light of that belief. Lewis's own closing words serve as a warning none of us can afford to ignore:
"Whenever we find that our religious life is making us feel that we are good — above all, that we are better than someone else — I think we may be sure that we are being acted on, not by God, but by the devil."
We who stand only by the grace of God — may we remember that grace, and may that remembrance lead us, as a first step, to open the pages of Mere Christianity.
About Author
faith.log
A journal that connects faith and everyday life. In each small piece of writing, we share the grace of God and the depth of life together.