“You believe in God,” says Christ, “believe also in me” (John 14:1)—“Believe also, act faith distinctly on me; faith divine, supernatural, that faith whereby you believe in God, that is, the Father.” There is a believing of Christ, namely, that he is the Son of God, the Savior of the world. That is that whose neglect our Savior so threatened unto the Pharisees, “If you believe not that I am he, you shall die in your sins” (John 8:24). In this sense faith is not immediately fixed on the Son, being only an owning of him (that is, the Christ to be the Son), by closing with the testimony of the Father concerning him. But there is also a believing on him, called “believing on the name of the Son of God” (1 John 5:13; so also John 9:36)—yea, the distinct affixing of faith, affiance, and confidence on the Lord Jesus Christ the Son of God, as the Son of God, is most frequently pressed. John 3:16, “God” (that is, the Father) “so loved the world . . . that whosoever believes in him” (that is, the Son) “should not perish.” The Son, who is given of the Father, is believed on. “He that believes on him is not condemned” (v. 18). “He that believes on the Son has everlasting life” (v. 36). “This is the work of God, that you believe on him whom he has sent” (John 6:29, 40; 1 John 5:10).
Communion with the Triune God (Wheaton, IL; Crossway; 2007) p. 99-100.