"You can lead a horse to water but you can't make him drink." I think Paul understood this principle when it came to the Torah. Was it enough to ensure a good life in the Promised Land? It was not (Rom 7). Throughout Romans and Galatians, Paul makes contrasts from several different angles. It is good to spend time reflecting on these contrasts, what is on the right side of the list and what is on the left side of the list.
Law v.s. Spirit
Flesh v.s. Spirit
Works v.s. Faith
Works v.s. Grace
Bondage (to sin) v.s Freedom
Condemnation v.s. Forgiveness
Hagar v.s. Sarah
Paul makes it clear that the Law is good (Rom 7:7ff). The problem is that people were attempting to use the law for what it was never designed to do nor able to do:
1) Forgive. The law does not forgive sin, it merely "defines" it. This made sin more powerful (Rom 7:13). It was as if sin took the law hostage and used it to kill people by separating them from their God (Rom 7:8). Yes, there were provisions in the law to seek forgiveness. However, the "ritual" itself did not attain the forgiveness, but was a demonstration of a contrite heart (Psalm 51). It was God who responded by granting forgiveness on the basis of his grace, not a keeping of the law.
2) Transform. The law instructs, defines, and prescribes penalties, but cannot transform a person. Even with law enforcement officers, you may get compliance at best. Perhaps this is the reason for Paul's curious choice of words, "For the flesh sets its desire against the Spirit, and the Spirit against the flesh…But if you are led by the Spirit, you are not under the Law (Gal 5:17-18)." You might have expected him to say the "flesh" instead of "Law." But as you can see from the contrasts above, Law and Flesh are associated with each other. The Law is about compliance, but the Spirit is about transformation. This is a very significant distinction. This is why Paul goes on and refers to the "deeds" of the flesh (Gal 5:19ff) v.s. "fruit" of the Spirit (Gal 5:22), not the "deeds" of the Spirit.
So, when Paul instructs us to be "filled with the Spirit (Eph 5:18)," he is not telling us merely to add more deeds into our lives. He is calling for a complete inner transformation of our inner selves through the power of the Spirit. How do we do this? We must purge ourselves of all that is not God and allow all that is God to fill us. God's thoughts must become our thoughts, His will our will. We must learn in humility and silence the mystery of godliness. Then we will see "fruit" in our lives rather than merely "deeds." Reflect on Galatians 2:20.