A30: The Spirit applieth to us the redemption purchased by Christ, by working faith in us₁, and thereby uniting us to Christ in our effectual calling₂.

1. Eph 1:13-14; John 6:37,39; Eph 2:8
2. Eph 3:17; 1 Cor 1:9

For further study see:

1. WSC 31: What is effectual calling?
2. WLC 67: What is effectual calling?
3. WCF CHAPTER 10: Of Effectual Calling
4. Dr. R.C. Sproul explains “effectual calling”, also known as “irresistible grace”:
   
5. Dr. Dennis Prutow explains WSC 29 & 30: