WSC Q.31: What is effectual calling?
Effectual calling is the work of God’s Spirit, (2 Tim. 1:9, 2 Thess. 2:13–14) whereby, convincing us of our sin and misery, (Acts 2:37) enlightening our minds in the knowledge of Christ, (Acts 26:18) and renewing our wills, (Ezek. 36:26–27) he doth persuade and enable us to embrace Jesus Christ, freely offered to us in the gospel. (John 6:44–45, Phil. 2:13)
WLC Q.67: What is effectual calling?
Effectual calling is the work of God’s almighty power and grace, (John 5:25, Eph. 1:18–20, 2 Tim. 1:8–9) whereby (out of his free and special love to his elect, and from nothing in them moving him thereunto) (Tit. 3:4–5, Eph. 2:4–5,7–9, Rom. 9:11) he doth, in his accepted time, invite and draw them to Jesus Christ, by his word and Spirit; (2 Cor. 5:20, 2 Cor. 6:1–2, John 6:44, 2 Thess. 2:13–14) savingly enlightening their minds, (Acts 26:18, 1 Cor. 2:10,12) renewing and powerfully determining their wills, (Ezek. 11:19, Ezek. 36:26–27, John 6:45) so as they (although in themselves dead in sin) are hereby made willing and able freely to answer his call, and to accept and embrace the grace offered and conveyed therein. (Eph. 2:5, Phil. 2:13, Deut. 30:6)
WCF 10.1.
All those whom God hath predestinated unto life, and those only, He is pleased, in His appointed and accepted time, effectually to call, (Rom. 8:30, Rom. 11:7, Eph. 1:10–11) by His word and Spirit, (2 Thess. 2:13–14, 2 Cor. 3:3,6) out of that state of sin and death, in which they are by nature to grace and salvation, by Jesus Christ; (Rom. 8:2, Eph. 2:1–5, 2 Tim. 1:9–10) enlightening their minds spiritually and savingly to understand the things of God, (Acts 26:18, 1 Cor. 2:10,12, Eph. 1:17–18) taking away their heart of stone, and giving unto them an heart of flesh; (Ezek. 36:26) renewing their wills, and, by His almighty power, determining them to that which is good, (Ezek. 11:19, Phil. 2:13, Deut. 30:6, Ezek. 36:27) and effectually drawing them to Jesus Christ: (Eph. 1:19, John 6:44–45) yet so, as they come most freely, being made willing by His grace. (Cant. 1:4, Ps. 110:3, John 6:37, Rom. 6:16–18)