The Catechism in Questions & Answers

428. What is meant by the term “the ministry of the Spirit”?

The “ministry of the Spirit” (2 Corinthians 3: 8) is the ministry that gives the Spirit. Through the dispensation of the gift of the Holy Spirit, those baptised with water receive childhood in God and the prerequisite for becoming a firstling.

The image of the ‘firstlings’ is derived from the “firstfruits” of Revelation 14: 4. This term designates those whom Jesus Christ takes unto Himself at His return. They are identical with the “bridal congregation” (see Questions 562 et seq.).