When John writes in 1:14 that God’s glory was revealed in the person of Jesus Christ, he describes that glory to be full of grace and truth. Grace is undeserved kindness and truth isn’t merely pointing to the content of what Jesus said, namely that it was void of that which is false, but also the complete trustworthiness of God in the fulfillment of his promises in Jesus Christ. In John 14, Jesus said that he is the truth and in 1 John 4 John writes that God is love. These are put on full display as the glory of God is revealed in person of Jesus Christ–not only in what he said, but who he is. And this corresponds precisely to John’s point of teaching about the incarnation of the 2nd member of the Trinity in this passage, in that Jesus Christ represents the clearest and fullest revelation of God ever given (v.18).
Nevertheless, think with me for just a moment what other attributes could have displayed God’s glory in the God-man, Jesus Christ. Perhaps he could have come with holiness and wrath, like the giving of the law at Mt. Sinai. He could have come with jealousy and vindication, as when the earth swallowed up thousands of Israelites following their idolatry. He could have come with fiery judgment, as was present in the annihilation of Sodom and Gomorrah. But when the Word became flesh, he was full of grace and truth.
In light of those possibilities, is it even conceivable to find a combination of 2 more significant attributes to have in One in whom you place your entire life? He is worthy of all our worship and all our trust.