In the Reformed tradition, vocation refers to God's effectual calling of sinners to Himself by His Spirit through the proclamation of the Gospel, which produces faith and enables the believer to embrace Christ. It also encompasses the 'calling' to every legitimate station in life and work, where the believer serves God and neighbor, reflecting the gospel truth that we are saved by grace alone for good works.
At the heart of the doctrine of vocation is the 'effectual calling' of God. This is not merely an external invitation, but the life-giving work of the Holy Spirit. As defined in Westminster Shorter Catechism Q.31, this calling is the work of God’s Spirit, whereby, convincing us of our sin and misery, enlightening our minds in the knowledge of Christ, and renewing our wills, he doth persuade and enable us to embrace Jesus Christ. It is this call that brings us from death to life, as seen in the progression of grace: Romans 8:30 declares, 'and whom he foreordained, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.' We are thus accepted in Christ, and because we are loved, we are called into the fellowship of His service.
The Reformed tradition, and particularly the 1689 tradition, emphasizes that once we have been effectually called, our daily lives—our work, our family, and our citizenship—become the theater for displaying the glory of God. We are not saved by our work, but we are saved for our work. 1689 LBCF Ch.3 §7 highlights that this doctrine of election and calling should lead us to 'diligence' in our obedience. Just as Peter exhorts us in 2 Peter 1:10, we are to 'give the more diligence to make your calling and election sure.' Our vocations in the world are the 'good works' prepared for us (Ephesians 2:10), meant to demonstrate that we are truly Christ's sheep, known by the fruit of our lives.