“For the law was given through Moses; grace and truth came through Jesus Christ.” (John 1:17)
This verse from John is a watershed verse because in a few simple words, it delineates the Old Covenant from the New; Jesus from Moses. In a very clear way, it summarizes the flow of redemptive history by reminding us that there is a difference between Moses and Jesus and the two were never intended to be mixed together.
Unfortunately, mixing them together is what many of us like to do. Grace scares us so we read this verse as though it’s a subtle warning and reminder that truth is meant to balance out grace. We read it as though truth polices grace and keeps it manageable. And of course by “truth,” we mean some sort of law or rule-keeping that somehow tames grace down a bit so it isn’t quite so free and threatening. It can be something we pull over from Moses or some rule or principle we find in the New Testament or in our religious environment. Either way, we read this as though grace needs balanced out by some sort of truth as if grace and truth were two opposing forces doing battle with one another because grace needs tempered by truth. It’s interesting that we never view it the other way around, where grace balances out truth. Our default is always a balancing out of grace with truth, never truth with grace.
But this verse is a both-and, not an either-or. Jesus is grace AND truth. John wasn’t issuing an ultimatum here, nor was he reminding us to temper grace with some version of truth as though grace is opposed to truth and truth to grace. Grace is not opposed to truth and truth is not in conflict with grace. John wasn’t offering us a set of balancing scales to make sure we’re balancing grace with appropriate amounts of truth. He’s not telling us to keep grace in check with truth. He’s not saying truth trumps grace. He’s talking about the supremacy of the New Covenant over the Old. The Supremacy of Jesus over Moses. Jesus is the embodiment of both truth (John 14:6) and grace (Titus 2:11-12) in their fullness (John 1:14). Jesus isn’t grace tempered by truth, but he’s the very fullness of both. He is what Moses wasn’t and never could have been.
Moses was an expression of truth in his time. The Old Covenant and the Law that came with it expressed truth for that age, but without grace. There is no grace in Moses – only works-based law and failure to obey that law perfectly, resulted in condemnation. In that sense, Moses was full of truth, but no grace. None. Enter Jesus, full of GRACE and truth! Jesus brought the remedy to our problem that Moses was only able to diagnose, but never cure. Adding law or rules to grace in order to tame it is anti-grace. The truth is, we’re in trouble and we need rescued and that rescue comes from outside of ourselves by grace. The truth is, all of us have sinned and fall short but God justifies us by grace, apart from law. Here’s how Paul worded it:
 But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction:  for all have sinned and fall short of the glory of God,  and are justified by his grace as a gift, through the redemption that is in Christ Jesus,  whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins.  It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. (Romans 3:21–26)
This is the gospel – grace and truth in their fullness are finally and fully revealed in Jesus, our substitute and redeemer. We can throw away the balance scales and enjoy this free gift we’ve been given because “…from his fullness we have all received, grace upon grace.” (John 1:16).