God is the Savior. He is the only Savior. And one of the ways He helps us remember that is by giving us the Sabbath, a day when we stop working and rest in Him. I love how God says it in this chapter: "Say to the Israelites, 'You must observe my Sabbaths. This will be a sign between me and you for the generations to come, so you may know that I am the Lord, who makes you holy.'" (vs 13)
The word translated holy in that verse is the Hebrew word Qadash, which means to be honored, to be treated as sacred. So what God is saying here is that we should keep the Sabbath day in order to remember that God is the one who honors us. He treats us as special, precious children.
It is because of this relationship that God saves us. He saves us because He loves us. He saves us because, in His eyes, we are valuable treasures. But we can only enjoy the advantages of this relationship when we take part in it. If our attitude is one of autonomy and self-sufficiency (remember that "plague" from the previous chapter?), we will work and work to save ourselves. That only leads to a dead end.
Since God is the only Source of life in the universe, we can’t find it without Him. We can’t work for it or obtain it on our own. He is the only one who creates and saves. And the Sabbath is a weekly reminder (even a confrontation!) that we are dependent upon God, and that He loves us and honors us as His children.