Novelty was not the goal of the Protestant Reformers when they set out to reform the medieval Western church. In fact, one of their major complaints against the pope and those who remained subject to him was that their theology was not ancient enough. The Reformers returned to Scripture and the teachings of the early church fathers to recover what had been obscured, and this recovery included the embrace of Trinitarian theology.
With the early church fathers, the Reformers were convinced that the doctrine of the Trinity is not an exercise in theological abstraction but is vital for understanding God’s character, purposes, and relationship with His people. One of the key insights of Trinitarian theology is that what Christ enjoys by nature, we enjoy by grace. As we look at today’s passage, we see the Son referencing the love that the Father had for Him from all eternity, love for the Son that preceded the Father’s sending Him into the world (John 17:23). Because of the personal relations between the three persons of the Trinity, we must understand that this love of the Father for the Son is definitional of who the Father and Son are. To be the eternally unbegotten Father is to love the Son and to be the eternally begotten Son is to love the Father.
God’s love for us, however, is of a different order. It is love born of grace. Father, Son, and Holy Spirit would still be Father, Son, and Holy Spirit even if God had never chosen to love us. Yet, one of the most wondrous aspects of our salvation is that when God chooses to love His people, it is with love that is the same in character as the intra-Trinitarian love between Father, Son, and Holy Spirit. Another way of putting this is to say that the relationship that the Son enjoys with the Father by virtue of His being the eternal Son, we enjoy by grace. In other words, the Father by grace—and by grace alone—showers on us the same love that He has for the Son. Speaking of us, Jesus says that the Father “loved them even as [He] loved me” (v. 23).
John Calvin reminds us that we enjoy this love not because we are inherently lovable but because we are united to Christ. Because we are in Christ by faith, we are God’s beloved children (1:12–13). God loves us with an enduring, undefeatable love because of Jesus. Calvin writes, “That love which the heavenly Father bears towards the Head is extended to all the members, so that he loves none but in Christ.”