Many members of our community are teachers, either as professionals or seasoned Church School volunteers. I would bet that almost all of them could tell you stories about how students can surprise us with their questions, often when we least expect it. About ten years ago, I was teaching Sunday School for a group of first and second graders. Our story for the day was a classic—Noah’s ark. I went all out for this lesson. I brought my entire assortment of puppets to reenact the story, I taught the class one of my favorite camp songs, and I planned a game about covenants and promises. The morning went well, and I was delighted when—at the end of the lesson—the quietest student raised his hand to ask a question.

I thought he would ask a question about one of the puppets. Or maybe about how Noah built the ark.

Instead, the six-year-old asked, very earnestly, “How do we know that God exists?”

Needless to say, I hadn’t quite prepared for this sort of question. I'd bet that most of you probably could have come up with a better answer than I did. I mumbled something unsatisfying, like, “Because the Bible tells us so.” He didn’t seem convinced.

Later that week, I asked friends what they would have said. They had all sorts of interesting answers: “Reality needs a first cause.” “Everything can’t come from nothing.” “Somebody needs to make sure that the world runs smoothly.” I noticed that most of their answers were focused on finding a logical proof for God’s existence, something that was irrefutable.

But when I brought their answers back to my student to see what he thought, he was unsatisfied with all of them. Except for one. He liked this reason: “God is like the love your parents or your friends show toward you. You know it because of its effects, because life wouldn't make sense without it."

Today’s Gospel is puzzling because it raises more questions than answers. It doesn’t give us much direction about how we’re supposed to follow Jesus’s teaching. Jesus calls himself the true vine and urges us to stay connected to him as branches to bear fruit. We're called to abide in Christ, just as Christ abides in us. The stakes are high. We’re told that the branches that don’t bear fruit are gathered, thrown into the fire, and burned. This passage gets our attention, but it doesn’t give us much guidance. Our questions might sound something like those of my young student. How do we know? How do we know when we abide in Christ? How do we know when we’re bearing fruit?

John’s letter gives us an answer. We stay connected with God, and our faith bears fruit, when we imitate God through love.

John admits, “No one has ever seen God.” God’s ways are so far above our own that we cannot grasp the full reality of God’s power in this life. God resides where logical proofs and scientific certainty cannot reach. But there is one thing we can do, and one way in which we can truly know God. John tells us: “If we love one another, God lives in us, and his love is perfected in us.”

Over the centuries, Christians have come up with many ways of understanding God and his covenant with us. The most enduring ones have returned to this central insight of our faith: that God is love. Hans Urs von Balthasar, a Roman Catholic theologian in the twentieth century, wrote that any human ideas about God or visions of Christian discipleship are absurd unless they lead us back to our experience of God’s love. As he put it, “Love alone is credible.”

We’re both suspicious of this idea and attracted by it. On one hand, our culture tends to prioritize the rational and scientific above other ways of knowing. Scientific thinking has been the source of much good, but we sometimes fall into the tendency of trying to explain everything reason when we know things in so many other ways. We know God not because we can sit down and calculate God’s existence. We know God because we see the fruits of God’s love all around us and within us.

This way of thinking has its risks. On our journeys of faith, there's a temptation to turn the idea that “God is love” into a cliché. We’re sometimes tempted to measure whether God is among us based on whether we feel a sense of love. We equate God’s love with feeling warm inside. God’s love is certainly not opposed to the warm and fuzzy, but it's bigger than that. Notice that when John describes God’s love, he isn’t describing a feeling. He’s describes an action: God sends his only son into the world. God becomes incarnate, walking among us, and embracing even the sweat, blood, and tears of the world.

When we’re not sure how to go about loving others, we can look to God’s example as a guide. God shows each of us divine love by giving us strength and grace everyday. We can channel that love by being a consistent and steadfast source of strength and encouragement to the people in our lives and to our communities. God shows us divine love in history by walking the earth as one of us. We can respond to this love by committing ourselves to being sources of light in the darkest places, by serving our neighbor even when we put our own comfort or social acceptance at risk. Just as God shows us love by being with us, we can show love by being with our neighbors, by showing up, even when it doesn’t benefit us.

When we live out our faith in this way, we truly bear fruit as branches on the vine. And what is most extraordinary about these times is that our acts of love turn out to be part of God's plan all along. Notice the provocative, even radical, way in which John phrases this sentence: “If we love one another, God lives in us, and his love is perfected in us.” Our response is God’s end game. God's plan is for us to get swept up in his work. God has given us a gift of love that is made perfect not when we receive it, but when we are transformed by it by participating in the beautiful and stunning reality of God's love.

How do we know that we abide in God? When God's love overflows from us and becomes the love that we extend to the neighbor.