If Jesus were to meet an atheist you know today, what do you think He would do? The answer to that question will heavily determine what you often do every time you encounter an atheist in your workplace, at your campus, or even on social media.
In Matthew 5:16, Jesus tells us, "In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven" (ESV). Believers like to look at this scripture and think that it's a command to go and preach the gospel. As important as it is to preach, not everything in the gospel can be preached without first exemplifying it to others.
The number one reason atheists are atheists is the inability of some Christians to act according to the what the Bible teaches. I'm not talking about our inability to go to church, to memorize scripture, or to follow rituals and traditions. We're good at that—not just Christians, but people in general. Even atheists have and may still do that.
But what many believers find hard to do is to love, unconditionally, everyone they come across. I admit that I have struggles with loving unconditionally because my broken and sinful nature tells me to be conditional in my compassion and affection.
An inability to love can first and foremost only be cured by experiencing a love that can match the lack of love in us. 1 John 4:7 tells us, "Beloved, let us love one another, for love is from God, and whoever loves has been born of God and knows God" (ESV). God is the full manifestation of love and He best shows that to us through Jesus Christ. Have you encountered the love of Jesus in such a way that it compels you to love others?
Many times, the love we believers have—just like everyone else—can be extremely conditional. But God says that love should be shared with everyone if we are in Him. He calls us to love our neighbor, love the lost, and even love our enemies to the point of sacrificing our selfish desires.
You may have some problems with an atheist brother or sister today. He or she might be challenging your belief and even ridiculing you by calling you stupid to believe in "unicorns and tooth fairies." It doesn't matter because if you really know the love of God and you have experienced it in a real way, your belief needs no defense and whatever defense you make now is only to win over a brother.
But unless we learn to ferociously love others, we can never win them over either to the faith or to us. That's how Jesus won us over—with ferocious love—and that's how He calls us to win others over as well, whether your brother is a believer as well or not.