To understand the reason behind God giving the Mosaic law, we have to understand the spiritual condition of man. Humans became spiritually dead, fearful, and separated from God when they sinned. By nature they became unrighteous. God was no longer a part of their lives, the intimacy was gone, and humans were spiritually and permanently joined to Satan. Their nature became like Satan’s. (John 8:44; 1 john 3:10.)
But God didn’t give up on the human race. His way back into their lives was done through promises and covenants: if the promise was believed, it was in force, God would bring it to pass, and righteousness would be accredited to the promisee. (Genesis 15:6; Habakkuk 2:4; Romans 4:13; Galatians 3:6-9.)
The first promise was made in the Garden of Eden when God promised to crush the serpent by the “seed of the woman.” God then covered the sins of Adam and Eve through the blood of an innocent animal when He killed the animal and clothed Adam and Eve with the animal’s skin; thus the teaching of, and the start of, animal sacrifice for the atoning of sin. We can see this carried down through Abel, Enoch, Noah, Abraham, Sarah, Issac, Jacob, Joseph and all who would receive the promises of God by faith.
So why the Mosaic law? Consider these thoughts. Beginning with Moses, God started a new nation, Israel. Not everyone of the two million Israelis (approximately) that came out of Egypt had faith in the promises of God. In fact, by far the majority died in the wilderness because of their unbelief (Hebrews 3:7-19; Numbers 14:11-24; Deuteronomy 1:26-36). But the law became a focal point that the people could obey. Knowingly or unknowingly obedience to the law had an element of faith. The obedience of faith: “If I keep the law, God will pardon my sins and bless me.”
Also, every nation must have a common law. Clearly, with the Israelis, as with any other nation, the law couldn’t be left to the individual to do what was right in his own sight. So God instituted a law that provided for basic civil relationships, justice, sanitation and health, equity and everything that makes a nation successful. God’s law at Sinai was unique also. Everyone came under the same law: king, priest, farmer, soldier, etc. The usual for laws of that day was the king and upper classes lived under one set of rules and the populous live under another. It should also be noted that the Sinaic Law incorporated much more mercy toward criminals than other ancient laws we’re familiar with. Of course, compared to modern, western Christian based laws of today they seem very harsh. But if you’ll consider that God was dealing with an ancient culture raised in harsh and violent conditions, people of that day would think our ways are weak. We can see this attitude from those who practice sharia law. Nonetheless, God introduced more merciful ordinances to a culture that was used to dealing even more harshly with offenders. Also, until the New Birth nobody had had the ability to walk in the “fruit of the Spirit” (Galatians 5:16-18), to walk in the God kind of love (Romans 14:8-10) and thus fulfill the perfect law of God. The Mosaic law was never a stopping point. The law of love and the fruit of the spirt are God’s perfect will for His people.
Furthermore, being a theocracy, Israel needed to understand the holiness of YHWH/God and, by default, just how far human nature was from that holiness: “Where there is no law there is no transgression” (Romans 4:15; 7:7). The law of Moses revealed the chasm of sin between the Creator and His creation. It still does. Because of the impossibility of humanity to walk in the holiness of God, God instituted the Levitical priesthood with the sacrifices and offerings to cover Israel’s sins (Hebrews 5:1). These sacrifices allowed for an unbroken covenant between God and the nation of Israel. When we accept Jesus as Lord and His eternal sacrifice for sin (Hebrews 9:24-28), we become citizens of the Kingdom of God (Philippians 3:20; Ephesians 2:17-22; Hebrews 12:28). The holiness that the law of Moses foreshadowed is now fulfilled in the spiritual Kingdom of God (Luke 17:20-21) and is the standard for eternity.
Think of the Mosaic law as a fence. I work at a school with students from pre-k to twelfth grade. The pre-k and kindergarteners are kept in a fenced area when they’re playing outside. The fence isn’t to punish them but to keep them safe. As long as they’re in the fenced area they cannot wander off nor can predators molest them. God used the Mosaic law to keep His covenant people safe. As long as they stayed within its boundaries they were safe from outside predators and were within the realm of His blessings. Outside that fence there were vicious enemies to molest them and a curse. A curse that fell upon the earth when sin entered the world. Today, through Jesus the Messiah, we’re not without law. In fact, we live by a higher law: the law of doing no evil to his neighbor: the law of the love of God. To love as Jesus loved us. The ordinances of the Mosaic law concerning food, new moons, festivals, and sabbaths are a foreshadowing of things to come (Colossians 2:16-23). Israel couldn’t keep the law, because the law doesn’t give the ability for humanity to fulfill all of its conditions. No law does. So, trying to keep the law of Moses is futile. If one ordinance is broken, then the law condemns and sin is committed. But grace through faith gives the recipient the ability to walk in the fruit of the spirit against which there is no law (Galatians 5:16-25). We are not obligated to keep the law of Moses, but we are held at a higher spiritual law: the law of love in holiness. Eternity holds things we have yet to see, and the Kingdom of Israel was to be foreshadowing of the eternal Kingdom of God. A kingdom of holiness, prosperity, and the perfect law of selfless love.