I think a better strategy is to confront a person with truths about human nature which every reflective person must acknowledge. Given these truths, which worldview offers the best explanation of them? And which worldview offers the best advice about what to do about them?
These are subjective questions, of course. But they are more immediate. More personal. Less cerebral. Christianity makes certain truth-claims about history and the nature of reality, and they are important. But at bottom it is a Way, not a Proposition. Commenting on Jesus' words in John 14:6 ("I am the way, the truth, and the life", Thomas à Kempis says "Without the Way there is no going, without the Truth there is no knowing, without the Life there is no living".
In Christianity's answers to the deepest questions of humanity (Who is well off? What does it mean to be good? What is the good life?) I hear whisperings, resonances, intonations. Something deep inside me responds "ah yes, only that can explain who I am, who I ought to be, and why I am not". Someone who does not hear the same whisperings is unlikely to convert. But you can challenge them to listen, and let the Holy Spirit take it from there.
Here are some observations that evoke those deep questions in me, and how Christianity whispers a response that my soul recognizes.
Consuming does not make us happyInside everyone is a voice that says "if I just had a little more money, enough for X and Y and Z, then I would be happy and content". But that voice is lying. This experiment has been done many many times, and it has never worked. If you're honest with yourself, you should be able to verify that the voice is never satisfied. It always wants "just a little more". Studies have shown that, above a certain income level necessary for basic needs, having more money does not make you happier. But even basic reflection should show you that this is the case.
Sexual freedom does not make us happyYou'd never know it from how the culture portrays it, but promiscuity and uncommital sex does not make you happy in any ultimate sense. This is also fairly well-confirmed. People that follow basic, conservative (Christian) sexual moral rules are just happier and more satisfied than those who don't. It is not even hard to see why. The fact that we are increasingly divorcing sex from commitment, at tremendous cost to ourselves, only shows that we are not very reflective and we trust what we see in movies more than our own experiences.
We do not do what we know is best for usThis one is strongest and, in a way, most shocking. Not only are we constantly pursuing courses of action which do not make us happy, but we know we are doing so and do it anyway. Furthermore, we choose not to pursue those things which we know do make us happy. Again, you should be able to confirm this easily by self-examination. Here are some examples to get you started:
- TV/YouTube/the Internet. Have you ever squandered an hour, or an evening, or several evenings, watching television you didn't even like, or YouTube videos you immediately forgot, or browsing internet sites you do not even consider that interesting? And have you ever thought afterward how you really should have been doing something else, which you actually prefer?
- New-Years resolutions. Everyone makes them. Everyone knows that keeping them would make him happier, more fulfilled, and a better person. Everyone breaks them. Swiftly.
- Conscience. Everyone has a conscience that gives them basic moral principles, and everyone violates it. Everyone knows they are flawed, everyone does things they know to be wrong.
- As an extreme example, there are many homeless persons who would rather stay homeless than give up their booze. I know of some. Surely it must be clear, even to themselves in moments of sober honesty, that this is wild foolishness. Is there a dark part of you that is almost that crazy?
Surely there are several possible explanations, and you will have to evaluate their explanatory power for yourself. You could construct a story according to which this is all a product or byproduct of an evolutionary process of competition and survival. But this is the Christian explanation: We are sick - no, we are dead. The voice that cries out for more and is never satisfied, like an Ungoliant in our breast, is bearing witness to a real need - but it is a need we cannot satisfy unless we are reborn. It is a need that shows we are incomplete. We are not what we were intended to be.
What Christianity offers is, in part, a vision of how to be transformed. How to fill the empty place that your inner voice alerts you to by, paradoxically, nailing that voice to a cross. Because only once it is dead can it be satisfied.
That is what I hear, when I listen. What are your whisperings?