In this portion of scripture we have contrasted two ways to live, the first is under the bondage of a works righteousness by which men try to justify their sinful behavior by doing good works such as circumcision, the second is to live by faith.
We are told the first way avails or has the power to accomplish nothing, which means it does not bring the person any closer to heaven, God’s favor, or a productive life. Then the apostle uses that great word “but” to contrast the unproductive life of works with the victorious life of faith, “but faith which works by or through love.” Faith in Jesus Christ is the key that unlocks the door of love.
The evidence of saving faith is love, which is the fulfillment of the law, because the law is summed up in these words, “"YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR STRENGTH, AND WITH ALL YOUR MIND ; AND YOUR NEIGHBOR AS YOURSELF." (Luke 10:27)
It is not love that saves the Christian but faith in Jesus Christ who fulfilled the law through His sacrificial death and resurrection imparts favor with God. Love always follows saving faith as the Holy Spirit produces the fruit of love through His work of sanctification or setting God’s people apart to fulfill His holy purposes.
The Christian is one by the grace of God who puts first things first – first faith then love!