How do we know that Christ's call to follow Him is effective?

The effectiveness of Christ's call is rooted in His divine authority and the work of the Holy Spirit. When Jesus called Matthew, He did not wait to see if Matthew would respond; He knew he would follow, demonstrating the certainty of His call. This is indicative of irresistible grace—when God calls His chosen ones, He equips them with the faith necessary for salvation. As believers experience that call, they have a new desire to follow Christ, transformed by His grace, which assures us that His call is never in vain.