The general call is the outward invitation of the gospel extended to all who hear the Word, while effectual calling is the internal work of the Holy Spirit that supernaturally enables only the elect to respond in saving faith. While the general call may be rejected, effectual calling is an act of God's almighty power that creates a new heart, ensuring that those called will certainly embrace Jesus Christ.
The general call consists of the external proclamation of the gospel to all, which may be neglected or rejected by the reprobate (Westminster Larger Catechism Q.68). By contrast, effectual calling is the secret, inward work of the Holy Spirit whereby God brings the elect from death in sin to life in Christ. According to the 1689 LBCF Ch.10 §2, the sinner is wholly passive until they are quickened and renewed by the same power that raised Christ from the dead. This internal call is an infallible pledge of salvation, as it includes the necessary grace to ensure the sinner is both willing and able to come to Christ.
Effectual calling is not merely a suggestion that a sinner can choose to accept or decline; it is a creative act. As Romans 8:30 declares, "And whom he foreordained, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified." Because the sinner is by nature dead in trespasses, God must first give a heart of flesh, as described in the Reformed tradition (1689 LBCF Ch.10 §2). This call is the manifestation of God’s eternal election, making the soul willing and able to embrace the gospel, grounded entirely in the free, special grace of God in Christ.