What does effectual calling mean in Christianity?

In Ephesians 4:4, Paul speaks of a calling to one hope, highlighting the unity and power of the Holy Spirit in the believer's journey. Effectual calling is when the Holy Spirit calls an individual to Christ, resulting in a transformation that allows them to respond to the gospel truth. Titus 3:5 explains that this calling is not based on our works but is according to God's mercy, which enables our regeneration. This doctrine assures us that salvation is ultimately a divine initiative, as every believer will experience genuine faith in response to this effectual call of grace.