How do we know that free grace is a true doctrine?

The doctrine of free grace is deeply rooted in scriptural truths such as Isaiah 55, which emphasizes that God offers His grace freely without any need for human merit. In salvation, God does not ask for anything but our acknowledgment of our need and thirst for Him. This aligns with the historic Reformed understanding that grace is given not as a reward but as a gift. Biblical passages like Ephesians 2:8-9 affirm that salvation is a gift from God, emphasizing that it is not by works that we are saved, but through faith in Christ alone. The assurance of this grace is central to the sovereignty of God in salvation.