How do we know that God's calling is effectual?

The doctrine of effectual calling is critical within Reformed theology, emphasizing that those whom God calls are inevitably drawn to Him. God’s Word, as affirmed in Isaiah 55:11, states, 'So shall my word be that goeth forth out of my mouth; it shall not return unto me void, but it shall accomplish that which I please.' This ensures that when God calls, it yields real fruit in the lives of those who are called, confirming that His salvific intentions are not in vain. It rejects the view that God merely hopes for all men to respond, affirming instead that those whom He calls and seeks will indeed respond to His grace.