When the Israelites did this, it marked their first actual involvement in what God was doing other than giving mental assent to His works. In the analogy to New Testament theology, this act is tantamount to accepting the blood of Jesus Christ for the remission of sins, and it symbolizes the protection from death through forgiveness God Himself supplied.
Repentance is not symbolized in this analogy until Israel left Egypt. But does Egypt represent sin? Only indirectly. Egypt represents the place of our bondage, the location in which we commit our sins. In the analogy, sin is something we leave behind when we accept the blood of Jesus Christ. What did Israel leave behind in Egypt that represents sin?
Remember that each Israelite who came out of Egypt represented over 400 years of Israel living in Egypt. Though they were slaves there, they lived in the area that Pharaoh describes in Genesis 47:6 as being the best land in Egypt. We know from Exodus 12 that they had houses because God told them to remain in their houses overnight. Those homes had furnishings, and just like any other family that has lived in one place for a long time, they had generations of family heirlooms.
They were not wealthy, but they had all the trappings of home. They had family "treasures" that belonged to great-grandma or great-grandpa and been handed down to the generation of the exodus. Now they were about to leave.
If we were in that situation, what would we take, and what would we leave behind? We have hundreds of possessions: houses, automobiles, furniture, pots and pans, pictures, mementos, figurines, knick-knacks, clothing—all kinds of things. What the children of Israel left behind—it does not matter what it was—represented sin. When we accept the blood of Jesus Christ and repent, we choose at that point to leave things behind that will hold us back on our journey to the Kingdom of God.
They literally took with them only what they could carry. Some of them may have had some carts, but even so, they could take only a fraction of what they possessed. They did not do any sacrificing in the wilderness because they even had too few animals to sacrifice.
What they left behind, all their excess baggage, represents sin. In Hebrews 12:1, Paul says to get rid of "the sin which so easily ensnares us" so that one can run the race—and that is what these people did. They left behind anything that would hold them back from reaching the Promised Land, their "sins."
John W. Ritenbaugh
Unleavened Bread and Pentecost