To know Jesus in both head and heart, by faith, is to experience salvation, for the one who knows Him has first been known by Him (Gal. 4:9). This may be referred to as salvific knowledge of God, and it is grasped through special (or divine) revelation—the Word of God.
In His glorious high priestly prayer (Jn. 17), Jesus reveals His heart for His followers. He earnestly asks that His glory might be made known to the elect. The reason? Such knowledge will strengthen their faith, allowing them to persevere in union with their Savior.
One of the central themes of this chapter is the connection between salvation in Christ and the proper knowledge of God. As Jesus said in John 17:3, “And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.” Indeed, salvation in Christ and the knowledge of God are intrinsically linked to one another.
Stephen Charnock, recognizing the great truth contained in this verse, wrote two entire discourses on it. The first, A Discourse of the Knowledge of God, focuses on how God makes Himself known to His creation.
The beginning of the first Discourse concerns itself especially with understanding why Jesus prayed in the manner that He did. Before one can begin to truly grasp why the knowledge of God is so vital to the health of the Church and the believer, one must first understand that “The glory of Christ, and the glory of the Father in and by Christ, is the security of the glory of the church and every believer.”
In the person of Jesus, God is most fully known, and in being made known to His creation, God is also most glorified. Afterall, Jesus is “The brightness of his glory, and the express image of his person,” (Heb. 1:3). As John earlier explained, “And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth” (Jn. 1:14). One of the reasons, then, that Jesus became incarnate was to glorify Himself (the Triune God) through making Himself known. God, who is above all and transcendent, condescended to our low estate, through taking humanity upon Himself, so that we may perceive and understand Him as He truly is. Charnock explained:
This knowledge of God is not only a knowledge of God and Christ in the theory, but such a knowledge which is saving, joined with ardent love to him, cordial trust in him, as 1 Cor, xiii. 12, ‘Then I shall know even as also I am known,’ i.e. I shall love and rejoice, as I am beloved and delighted in by God. It is not only a knowledge of God in his will, but a knowledge of God in his nature; both must go together; we must know him in his nature, we must be obedient to his will. The devil hath a greater knowledge of God’s being than any man upon earth, but since he is a rebel to his will, he is not happy by his knowledge. It must be such a knowledge as leads to eternal life, and hath a necessary and infallible connection with it, as the effect with the cause, which is not between a speculative knowledge and salvation. It must be therefore such a knowledge which descends from the head to the heart, which is light in the mind and heat in the affections; such a knowledge of God as includes faith in him.
To know Jesus in both head and heart, by faith, is to experience salvation, for the one who knows Him has first been known by Him (Gal. 4:9). This may be referred to as salvific knowledge of God, and it is grasped through special (or divine) revelation—the Word of God. God makes Himself known in this way only to His elect through the proclamation of the Gospel of Jesus Christ.