This spillover of joy onto other people is called love. So you are always nicer to people when you feel happy about your future. Hope fills you with joy and joy spills over in smiles and kind words and helpful deeds. It won't be hard, then, to help people see that the good news of Christianity fits our need perfectly. Most people not only long for joy, but also for the great freedom of being so full in ourselves we can live for others.
Nothing shows the fullness and freedom of the human soul more than love.
Therefore, deep down people want to love. You can tell this by how many people admire Mother Teresa. Deep down we wish we were so full that our lives were a constant spring of life-giving water satisfying the needs of others. But instead we are confronted by the puny reality of our anxious, covetous hearts. Most of the time people are obstacles to our feeble pursuits of pleasure or threats to our fragile peace of mind.