John 1:16, 17 : From his fullness we all received grace upon grace. For the law was given through Moses. Grace and truth were realized through Jesus Christ.
As it says in verse 14, Jesus is full of grace and truth. In verse 16 it says that because Jesus is full of grace, we receive it over and over again. This is a common theme in Christianity. Jesus gives us what He is already full of. We are to give to others out of the love that we are filled up with from God. God doesn’t expect us to come up with love out of nothing. He gives it to us out of His fullness. This one way to contrast Jesus Christ with the law of Moses.
The law of Moses was a very good thing in that it defined God’s holy requirements for man. Knowing God’s requirements does not make it any easier to do them, it just makes us aware of them. The law doesn’t cause us to understand the truth. We don’t get to ask “Why” when faced with a legal requirement. Imagine that you are pulled over in a car. You can’t strike up a conversation with the officer about why it is against the law to speed. The only truth the law cares about is whether or not you broke it.
Since Jesus is full of grace and truth we are given favor and told about why things are the way they are. In a world of law, this makes a big difference. It’s nice to know why something is the way it is. It is also nice to be favored by the judge. This is not to say that the judge is going to let us off easy just because He likes us. God would not be a good judge if He showed favoritism. The law is good because it clearly defines good and bad.
The law tells us what “good” means (Romans 7: 7, 8). God is good and will live by His own laws. He will not tolerate any lawbreakers (Romans 2:12-16). It isn’t that He’s mean, He’s just upholding the law for the sake of justice and goodness. The Bible shows us that Israel was unable to get to God by the law. So how does Christianity work if God didn’t get more lenient and man didn’t get any better? Jesus made the difference by paying the price for our sin and God sees what Jesus did. What Jesus did was acceptable to God as punishment for the wrong doing.
Because the price has already been paid, God is able to freely show us His favor or grace and to talk to us about the truth as friends (John 15:14, 15).