Love is the test of Spiritual authenticity. In other words, a growing ability to love with God's love authenticates our New Birth.
Many things in life are difficult to discern. From the outside they look the same––fool’s gold, fake Gucci purses, counterfeit $100 bills. The Christian life works the same way. The apostle John wants us to know that there is a fool proof test of New Birth––growing capacity to love.
This my surprise you. If we are saved by faith alone through grace alone how can love be the test? Listen to 1 John 3:14, "We know that we have passed out of death into life, because we love the brothers. Whoever does not love abides in death."
Why is love the test? Here is the answer. New Birth means “spiritual life.” It is resurrection, a passing from death to life. This begs the question, "what does it mean to be spiritually alive?" “Spiritual life” means that God has opened the lines of communication with us. God speaks to us. What does God communicate to all those truly born again? It is something unique, something that sets them apart. It indicates that they belong to him.
Note: God does communicates with some unbelievers, i.e. Nebuchadnezzar, Balaam, Judas, etc. But there is one special subject he never opens to unbelievers. That subject sets believers apart. It also motivates love.
Here is the unique subject. To the regenerate, God communicates the glory of God in the face of Christ (2 Cor. 4:6). Another way to say this is that God reveals his goodness to them.
Where do we see this goodness? The glory of God in the face of Christ is most clearly revealed in the cross of Christ. This knowledge usually comes in ever deepening waves. The effects are manifold and go on forever. This is the assumption behind these statements by the apostle, John.
1 John 2:9–10 "Whoever says he is in the light and hates his brother is still in darkness. Whoever loves his brother abides in the light, and in him there is no cause for stumbling."
1 John 4:7–8 "Beloved, let us love one another, for love is from God, and whoever loves has been born of God and knows God. Anyone who does not love does not know God, because God is love."
Are you growing in love?