What does the Bible mean when it speaks about “glory”? The glory of God was revealed to Moses at Sinai- and what he heard was the declaration of God’s Name or character, that Yahweh is a God full of grace, mercy, truth, justice, judgment etc. (Ex. 33:19; 34:6,7). Jesus alludes to what happened at Sinai by saying that He has “glorified you… manifested your name” (Jn. 17:4,6). Whenever those characteristics of God are recognized, manifested or openly shown, God is glorified. In this sense, God is the “God of glory” (Ps. 29:3 etc.). He is totally associated with His Name and characteristics- it’s not that He just shows those particular attributes to men, but He Himself personally is someone quite different. He is His glory. And this is why Jn. 17:5 parallels His glory with God’s very own “self”.
That glory of God was of course always with God, right at the beginning of the world. He hasn’t changed His essential characteristics over time. The God of the Old Testament is the same God as in the New Testament. As John begins his Gospel by saying, the essential “Word”, logos of God, His essential plans, intentions, personality, was in the beginning with Him. It was “made flesh” in the person of Jesus (Jn. 1:14), in that the Lord Jesus in His life and especially in His death on the cross revealed all those attributes and plans of God in a concrete, visible form- to perfection.
The request of Jesus to be glorified is therefore asking for the Name / attributes / characteristics / glory / word of God to be openly revealed in Him. Surely He had in mind His resurrection, and the glorifying of God which would take place as a result of this being preached and believed in world-wide.
But in what sense was this the glory which Jesus had with God before the world was? As we have said, the “glory” of God was revealed to Moses at Sinai in Ex. 34 as the declaration of His character. In this sense, the Lord Jesus could speak of having in His mortal life “that glory which was with [the Father]” when the [Jewish] world came into existence at Sinai (Jn. 17:5 Ethiopic and Western Text). It was that same glory which, like Moses, He reflected to men. But according to 2 Cor. 3:18, the very experience of gazing upon the glory of His character will change us into a reflection of it. There is something transforming about the very personality of Jesus. And perhaps this is why we have such a psychological barrier to thinking about Him deeply. We know that it has the power to transform and intrude into our innermost darkness.
There is essentially only one glory- the glory of the Son is a reflection or manifestation of the glory of the Father. They may be seen as different glories only in the sense that the same glory is reflected from the Lord Jesus in His unique way; as a son reflects or articulates his father’s personality, it’s not a mirror personality, but it’s the same essence. One star differs from another in glory, but they all reflect the same essential light of glory. The Lord Jesus sought only the glory of the Father (Jn. 7:18). He spoke of God’s glory as being the Son’s glory (Jn. 11:4). Thus Isaiah’s vision of God’s glory is interpreted by John as a prophecy of the Son’s glory (Jn. 12:41). The glory of God is His “own self”, His own personality and essence. This was with God of course from the ultimate beginning of all, and it was this glory which was manifested in both the death and glorification of the Lord Jesus (Jn. 17:5). The Old Testament title “God of glory” is applied to the Lord Jesus, “the Lord of glory” (1 Cor. 2:8; James 2:1). It is God’s glory which radiates from the face of Jesus Christ (2 Cor. 4:6). Jesus is the brightness of God’s glory, because He is the express image of God’s personality (Heb. 1:3). He received glory from God’s glory (2 Pet. 1:17). God is the “Father of glory”, the prime source of the one true glory, that is reflected both in the Lord Jesus and in ourselves (Eph. 1:17). The intimate relation of the Father's glory with that of the Son is brought out in Jn. 13:31,32: " Now is the Son of man glorified, and God is glorified in him; and God shall glorify him in himself, and straightway shall he glorify him" .
What all this exposition means in practice is this. There is only “one glory” of God. That glory refers to the essential “self”, the personality, characteristics, being etc. The Lord Jesus manifested that glory in His mortal life (Jn. 2:11). But He manifests it now that He has been “glorified”, and will manifest it in the future day of His glory. And the Lord was as in all things a pattern to us. We are bidden follow in His path to glory. We now in our personalities reflect and manifest the one glory of the Father, and our blessed Hope is glory in the future, to be glorified, to be persons who reflect and ‘are’ that glory in a more intimate and complete sense than we are now, marred as we are by our human dysfunction, sin, and weakness of will against temptation. We now reflect that glory as in a dirty bronze mirror (2 Cor. 3:18). The outline of God’s glory in the face of Jesus is only dimly reflected in us. But we are being changed, from glory to glory, the focus getting clearer all the time, until that great day when we meet Him and see Him face to face, with all that shall imply and result in. But my point in this context is that there is only one glory. That glory was with God from the beginning. Jesus was in the mind and plan of God from the beginning. It was God’s original plan to resurrect and glorify and justify His Son. And in Jn. 17:5, Jesus is asking that this will happen. The glory which Jesus had “before the world was” is connected with the way that He was “foreordained before the foundation of the world” (1 Pet. 1:20), the way God promised us eternal life (through His Son) before the world was (Tit. 1:2). 2 Tim. 1:9 speaks of us as being called to salvation in Christ “before the world began”, He “chose us in Him before the foundation of the world” (Eph. 1:4). In the same way as we didn’t personally exist before the world began, neither did Christ. Indeed 1 Cor. 2:7 speaks of us having some form of glory with God “before the world began”. It’s the idea of this “one glory” again- God’s glory existed, and it was His plan to share it with His Son and with us; and He speaks of those things which are not as though they are, so certain are they of fulfilment (Rom. 4:17). In Jn. 17:5, the Lord Jesus is ‘pleading the promise’ of these things.
We need to remember that the Lord was speaking, and John was writing, against a Jewish background. The language of 'pre-existence' was common in Jewish thinking and writing. To be 'with God' didn't mean, in Jewish terms, to be up there in heaven with God literally. Mary had favour para God (Lk. 1:30) in the same way as Jesus had glory para God, but this doesn't mean she pre-existed or was in Heaven with God with her "favour". The Torah supposedly pre-existed, everything on earth was a pattern of the pre-existing ideas of those things which were held in the plan and mind of God in Heaven. John 17:5 has reference to these things: "And now, Father, glorify me in your own presence with the glory that I had with you before the world existed". The Talmud and Genesis Rabbah speak of the "Throne of Glory" pre-existing before the world existed. And the Lord Jesus seems to be alluding to that. The Jewish mind wouldn't have understood the Lord Jesus to be making any claim here to have bodily, physically existed before birth. Peter reflected Jewish thinking when he wrote (albeit under inspiration) that Jesus was "foreknown" before the foundation of the world (1 Pet. 1:20 ESV). Think through the implications of being "foreknown"- the Greek word used is the root of the English word 'prognosis'. If God 'foreknew' His Son, the Son was not literally existent next to Him at the time of being 'foreknown'. Otherwise the language of 'foreknowing' becomes meaningless.