How do we know the effectiveness of the armor of God?

The effectiveness of the armor of God is underscored in Ephesians 6:13, where it states that believers must take up the whole armor of God to withstand in the evil day. Each characteristic of the armor serves a specific purpose, collectively providing not only defensive strength but also offensive capability through the word of God, which is the sword of the Spirit. The assurance comes from both the promise of God's provision and the historical reality of believers who have triumphed over spiritual adversities by relying on this divine armor. The doctrine emphasizes that through faith and the application of this armor, believers can actively combat spiritual deception and remain secure in their salvation.