When the Israelites arrive at Mt. Sinai in Exodus 19, the description given of it terrifies them. God is there on the mountain in thunder, lightning, and darkness. A trumpet sounds from the top of the mountain to announce God’s presence there. This is not a mountain for playing on or enjoying the sights. This is God’s mountain and it is not to be trifled with.
God instructs the Israelites on an important lesson they will need to continuously learn over the course of their lives: what it means for God to be holy. No sinner can enter God’s holy presence. To do so means swift destruction. Here, the people are ordered to put to death anyone who comes up the mountain. This idea of holiness will be a major feature of the tabernacle as well. If you are a sinner, you can’t come in, and that’s for your own safety.
The text doesn’t make any mention of people testing this restriction. In fact, they all seem to realize this isn’t something to mess around with. This is why it’s so peculiar that, just a few chapters later in Exodus 24, God appears to be breaking His own rule. He commands Moses, Aaron, Aaron’s sons, and seventy elders of the people to do exactly what He said not to do. They are to come up on the mountain to meet Him.
Is God’s Word true or isn’t it? Is His holiness something to be concerned about or isn’t it? It would appear God isn’t not actually all that serious about His holiness and the effects of sin, except that He demonstrates His unwillingness to tolerate sin in His presence on a number of occasions. So what makes this group any different?
The answer is, of course, not in what the Israelites do, but in what God does. In this case, God makes a covenant with His people. Moses makes a sacrifice of some oxen and uses some of the blood to splash on the people. The people had just affirmed that they would follow God, and so now God seals the deal in claiming them as His own.
The fact that Jesus uses this same terminology at the Last Supper is not by accident. It is by the blood of the sacrifice that we are enabled to draw near to God. In both cases, the culmination is the same. Moses, Aaron, and the rest draw near to God and see Him in His holiness and share a meal together. The disciples also draw near to God and share a meal with Him. The meal is a declaration of the relationship God has established with them. They are His people now and He desires to be with them in the same sort of intimate relationship one might share with family.
What is further of interest is how God begins the encounter at Sinai. He declares that they will be His treasured possession, a kingdom a priests and a holy nation. This is a baptismal pronouncement, for this is what we become in our own baptism. Thus, God prepares the people to enter into His presence by baptism. It is baptism that makes us fit to be with God without fear. It is this washing that makes us holy, holy as God Himself is holy. So, just as God teaches the disciples about how sin and holiness relate, He also teaches about how baptism and communion relate. Thus, what Jesus does at the Last Supper is the same lesson God has been teaching His people all along.