How shall we live? What is the good life? What is the value of a person? What is my place in this world? Is God active in this world? These are questions that have been asked in every culture and in every era. From the Hebrew concept of Shalom (wholeness/well-being) to the Greek concept of Eudaimonia (happiness) and even to the American notion that all people have the right to life, liberty, and the pursuit of happiness, great thinkers have pondered what it means for humans to flourish.
The doctrine of vocation uniquely answers these questions. A certain level of security, prosperity, and freedom are essential components of human flourishing. God provides these components by working through humans in their stations in life such as parents and police (security), farmers and bankers (prosperity), and soldiers and governments (freedom).
And yet there is more for which we strive. We are the type of beings whose wonderment drives us to the pursuit of knowledge, justice, and achievement. In short, we desire to be justified. We want to be valued. We want to be right or just. We strive for epic-ness. But no mere human adulation will satisfy. Nor can we justify ourselves before God with our broken lives.
God justifies Christians through Christ and then uses them. God adds another component to human flourishing: purpose. He uses Christians in his economy of love to take care of the world. He lifts us from the ordinary to accomplish the extraordinary, even as we pursue ordinary tasks. For the Christian, these stations become callings or vocations.
This can only be fully appreciated if the Christian knows that he or she is free from pleasing God through works. Once the Christian is freed from this burden the whole of the Christian life is reoriented to the free exercise of love towards neighbor. It is the highest calling, the truly good, flourishing, and happy life.