John the Baptist testifies to the Deity of Jesus
John the Baptist confirms the Apostle John’s teaching that Jesus is God in the flesh. He declares that Jesus, Who was born after him, actually preceded him in existence. John also declares that Jesus was greater than he was. John the Baptist is very clearly declaring Jesus to be the Eternal God become flesh.
In Jesus we receive an overflow of God’s grace because of God’s grace
All humans receive an overflow of grace from Jesus. All good gifts (food, health, etc.) come because of God’s grace. Believers receive an even greater abundance of grace in Jesus (forgiveness of sins, reconciliation with God, etc.) This grace comes to us because of God’s grace. In other words, God is good to us because God is good. Our merit or lack of merit is never in the equation.
God gave us the Law through Moses
It would seem that God giving us grace because of grace would make the Law unnecessary and even contrary to the nature of God. However, John tells us that God gave us His Law through Moses. Moses received the Law directly from the mouth of God. In fact, the Ten Commandments were written in stone by the very finger of God (Exodus 31:18). Therefore the Law is holy and good if it is used correctly (1 Timothy 1:8).
God gives us grace and truth through Jesus
Just as the Law came through Moses, God’s grace and truth come to us in the person of His Son, Jesus Christ. The Law was given to condemn us and show us that we have only merited wrath. This is so that we might seek God’s favor completely apart from our merit; this is salvation by grace. This grace comes to us through Jesus Christ. This reconciling of us to God is in accordance with all the Law, justice, righteousness, holiness, and truth. Therefore in Jesus we find the truth, or the correct understanding of the Law in relation to Grace.
God is seen in the person of Jesus
No man can come to God. However, in Jesus, God has come to man. Therefore the only fountain of grace and truth is Jesus. In Jesus we are reconciled to God. You could summarize John 1:15-18 this way:
God does not operate on the basis of our merit but on the basis of His own merit and gracious character. This merit and gracious character are found overflowing from the person of Jesus. The only way to obtain the favor of God is in the person of Jesus Christ.
We must learn to use the Law correctly. The Bible is not a list of things we do to bring down God’s favor. We must use the Law to show men their complete lack of merit. Then we must then point men to Jesus where God’s grace and truth overflow. Salvation is entirely by grace because of God’s grace. Therefore, He alone is to be praised. We must praise Him for His grace.