Answer: The term effectual call, as related to salvation, comes from Chapter X of the 1647 Westminster Confession of Faith. The effectual call is understood as God’s sovereign drawing of a sinner to salvation. The effectual call to a sinner so overwhelms his natural inclination to rebel that he willingly places faith in Jesus Christ. The apostle Paul refers to the effectual call when he writes, “It is God who works in you to will and to act in order to fulfill His good purpose” (Philippians 2:13). The necessity of the effectual call is emphasized in Jesus’ words, “No one can come to me unless the Father who sent me draws them” (John 6:44).
Paul further affirms that God must impress His will on the natural state of man when he writes that those who oppose God “must be gently instructed, in the hope that God will grant them repentance leading them to a knowledge of the truth” (2 Timothy 2:25). The apostle Peter writes that God “called us by his own glory and goodness” (2 Peter 1:3). Peter’s use of the Greek word kaleo, which is translated “called,” expresses the action of God calling sinners. Whenever kaleo is used in the participial form, as it is in this passage, with God as the subject, it refers to the effectual call of God on sinners to salvation. Kaleo carries the idea that a sinner is being drawn to God rather than simply invited to come.
The effectual calling is more commonly known as “irresistible grace,” which is the I in the acronym TULIP. The doctrine of effectual calling is closely related to the doctrine of total depravity, the T in TULIP. Since the unregenerate man is “dead in transgressions and sins” (Ephesians 2:1), he is incapable of reaching out to God or responding to the gospel of Jesus Christ on his own. “There is no one righteous, not even one; there is no one who understands; there is no one who seeks God” (Romans 3:10–11). This state of total depravity makes the effectual calling of God necessary to give anyone the opportunity for salvation.
Jesus said, “For many are invited, but few are chosen” (Matthew 22:14). In this statement, Jesus distinguishes between the general call that everyone receives by hearing the gospel and the effectual call that leads to salvation. The effectual call is also taught in passages such as Romans 1:6, where Paul greets the believers as those “who are called to belong to Jesus Christ”; and Acts 16:14, where Luke says of Lydia that “the Lord opened her heart to respond to Paul’s message.” The effectual call, therefore, is God’s action toward the elect, those whom He chose in Christ “before the creation of the world to be holy and blameless. . . . He predestined [them] for adoption to sonship through Jesus Christ” (Ephesians 1:4–5).
The general call, on the other hand, is for all of humanity, not just the elect. The famous passage, “For God so loved the world that he gave his one and only Son, that whoever believes in Him shall not perish but have eternal life” (John 3:16), portrays God’s general revelation to everyone in the world. The gospel is available to everyone, but, because of humanity’s sinful nature and total depravity, no one will turn to God without God first impressing Himself on them.
SOURCE: GotQuestions.org