For Martin Luther, vocation is nothing less than the locus of the Christian life. God works in and through vocation, but he does so by calling human beings to work in their vocations. In Jesus Christ, who bore our sins and gives us new life in his resurrection, God saves us for eternal life. But in the meantime he places us in our temporal life where we grow in faith and holiness. In our various callings—as spouse, parent, church member, citizen, and worker—we are to live out our faith.
Read Source: Martin Luther on Vocation and Serving Our Neighbors