How do we know the effective calling of God is true?

The effectiveness of God's calling is assured through the testimonies recorded in the Scriptures, including the stories of Matthew and Zacchaeus, who both experienced transformative encounters with Christ. Their willingness to respond was not merely a human decision but a manifestation of God's grace working in their hearts. The Apostle Paul affirms in Ephesians 1:4-5 that believers are chosen before the foundation of the world, indicating that God has a plan for His elect that guarantees their response in faith. Additionally, the persistent work of the Holy Spirit in convincing and converting sinners serves as a testament to the truth of this doctrine; those whom God calls will inevitably come to Him.