One of the doctrines of grace has commonly been called “irresistible grace.” This basically means that a sinful heart cannot refuse the sovereign work of God in regeneration. God is sovereign over the human heart and will. The term “irresistible grace” can be misunderstood and wrongly interpreted, so some have favored other terms like “effectual grace” or “efficacious grace.” Herman Bavinck wrote some helpful notes on the background of this term:
The term “irresistible grace” is not really of Reformed origin but was used by Jesuits and Remonstrants to characterize the doctrine of the efficacy of grace as it was advocated by Augustine and those who believed as he did. The Reformed in fact had some objections to the term because it was absolutely not their intent to deny that grace is often and indeed always resisted by the unregenerate person and therefore could be resisted. They therefore preferred to speak of the efficacy or of the insuperability of grace, or interpreted the term “irresistible” in the sense that grace is ultimately irresistible.
The point of the disagreement, accordingly, was not whether humans continually resisted and could resist God’s grace, but whether they could ultimately — at the specific moment in which God wanted to regenerate them and work with his efficacious grace in their heart — still reject that grace. The answer to this question, as is clearly evident from the five articles of the Remonstrants, is most intimately tied in with the doctrine of the corruption of human nature; with election (based or not based on foreseen faith); the universality and particularity of Christ’s atonement; the identification of, or the distinction between, the sufficient call (external) and the efficacious call (internal); and the correctness of the distinction between the will of God’s good pleasure and the revealed will in the divine being.
Whereas the Remonstrants appealed to Isa. 5:1–8; 65:2–3; Ezek. 12:2; Matt. 11:21–23; 23:37; Luke 7:30; John 5:34; and Acts 7:51, and to all the exhortations to faith and repentance occurring in Scripture, the Reformed theologians took their cue from the picture Scripture offers of fallen humanity as blind, powerless, natural, dead in sins and trespasses (Jer. 13:23; Matt. 6:23; 7:18; John 8:34; Rom. 6:17; 8:7; 1 Cor. 2:14; 2 Cor. 3:5; Eph. 2:1; etc.), and from all the forceful words and images with which the work of grace in the human soul is described (Deut. 30:6; Jer. 31:31; Ezek. 36:26; John 3:3, 5; 6:44; Eph. 2:1, 6; Phil. 2:13; 1 Pet. 1:3; etc.). So they spoke of the efficacy and invincibility of God’s grace in regeneration and articulated this truth in a confession at the Synod of Dort.
So in its 3rd/4th section, the Canons of Dort reject the errors of those who say that “when God intends man’s regeneration and wills to regenerate him,” man may resist God and the Holy Spirit; “and that it therefore remains in man’s power to be regenerated or not.” (RE Para. 8). If a person says that ultimately a human can reject the will of God and the power of the Holy Spirit in regeneration, that person is denying the efficiency of God’s grace in our conversion, and subjecting the working of God to the will of man, which is contrary to what Scripture teaches (Eph. 1:19, 2 Thes. 1:11, 2 Pet. 1:3, etc.). In other words, those who deny that God’s grace is ultimately irresistible are denying God’s sovereignty.