Q. 34: What is effectual calling?
A. Effectual calling is the work of God’s Spirit, whereby convincing us of our sin and misery, enlightening our minds in the knowledge of Christ, and renewing our wills, He does persuade and enable us to embrace Jesus Christ freely offered to us in the Gospel.
But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth, to which He called you by our gospel, for the obtaining of the glory of our Lord Jesus Christ. 2 Thessalonians 2:13-14