1 John 4:9 - Joseph Benson’s Commentary on the Old and New Testaments

In this was manifested the love of God Namely, most eminently above all other instances thereof; because that God sent his only-begotten Son into the world That is, evidently, sent him, who was his only-begotten Son before he was sent. “This,” as Macknight justly observes. “is an allusion to our Lord's words, John 3:16, God so loved the world that he gave his only-begotten Son, &c. Christ is called God's only-begotten Son, to distinguish him from all others, who in Scripture are called the sons of God; and to heighten our idea of God's love to us, in giving a person of such dignity, and so beloved of God, to die for us. It is supposed, that by giving Christ the title of God's only-begotten Son in this passage, the apostle intended to overturn the error of Ebion and Cerinthus, who affirmed that Christ was not God's Son by nature, but that, like other good men, he was honoured with the title of God's Son on account of his virtues; in which opinion these heresiarchs have been followed by some in modern times. They, however, who hold this opinion ought to show a reason why the epithet of the only begotten is appropriated to Christ.” That we might live through him That the sentence of condemnation to the second death, to which we were obnoxious, might be reversed, and that being justified by living faith, and regenerated by the quickening Spirit of God, we might live a spiritual life in the divine favour, and in union with Christ here, and might be conducted to eternal life hereafter.