One of the clearest examples of God showing his glory was when Moses wanted to see God’s glory, and he said, “Show me your Glory.” (My initial reaction to this verse was to pop in an old Third Day album and listen to Mac Powell sing like a songbird, but I resisted).

But, back to the subject at hand…(really, you can stop laughing now) God answers Moses by saying, “I will cause my goodness to pass in front of you and I will have compassion on whom I will have compassion” (Exodus 33:19). Just so we’re on the same page, Moses wants to see God’s glory and God says he will cause his goodness to pass in front of him.
Then, God fulfills his promise to Moses. Moses stood on Mt. Sinai and “the lord came down in the cloud and stood there with him and proclaimed his name the lord. And he passed in front of Moses proclaiming “the lord the lord, the compassionate and gracious god, slow to anger abounding in love and faithfulness, maintaining love to thousands and forgiving wickedness, rebellion, and sin (Ex 34:5-7).
The two important Hebrew words are hesed (variously rendered; steadfast love, mercy, covenant love, graciousness) and met (truth or truthfulness). hased and met are used over and over to describe God’s compassion or goodness in the Old Testament.
The essential thing to grasp is that God’s glory is supremely his goodness
Now, fast-forward to John’s allusion to Exodus in John 1:14. John already has the reader in Exodus; a Greek speaking Jew would have read the beginning of 1:14 more like this, “the Word pitches his tabernacle, or lived in his tent, amongst us” (carson). So, John is already taking his readers to chapter 25, but then he states, “and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.” John has seen “his glory” glory that can only be from the father, and the only one who can possess this glory must be from the Father (Jn 1:18)
Grace and truth is John’s word pairing that relates back to hesed and met. Carson seems to think that John is moving his readers back to Exodus and that the glory (goodness) passing in front of Moses was now incarnate, dwelling among them, and they have seen his glory, word-made-flesh……. God’s ultimate self-revelation.
So, how does this relate to the Cross?
It relates to the cross because Jesus, the God-man, is most glorified in the cross, (John 7:39; 12:16; 13; 31-32) therefore, God is most glorified in the cross. And, what did we say God’s glory was? His goodness. God’s ultimate glory was in the cross because he displayed the ultimate good. This is why Jesus Christ is the true/real/ultimate revelation of God (jn 1:9).
With this in mind, when we read that God loves the world ( Jn 3:16) we should view it in light of God’s character because it took the ultimate revelation of God to display his love for a world that did not know Him. John 3:16 shouldn’t give us warm fuzzies, as if we were lovable, but it should testify to God’s character— that he loved a world that hated him.
In short, God’s glory is found in the cross of Christ because the cross displays the perfect goodness of God’s character, in that, Jesus, the perfect and spotless lamb of God, substituted himself for a people who were in rebellion against him.
Just for a second, think of God’s glory (Ex 24:16/ Is 6) …. How majestic He is and how zealous He is for his own glory (Isaiah 48:9-11)…
Now think of the amount of glory God has (if it could be quantitative) and relate it to how much goodness it took for God to redeem his people. It’s sobering…….(Rom. 3:10-12; 14:23: Heb. 11:6)…… It took nothing less than the God who is necessarily perfect in goodness and power to redeem such a lost world.
Dwell on God’s goodness in view of his awesome glory, and we’ll begin to understand 1 Corinthians 1:29 “so that no one may boast in God’s presence.