The Law
before the fallThe Bible is very clear in saying that you can't save yourself by following the Law--that's impossible for humans to do. However, if the law isn't any good for that, what's the point of having it at all?
There is a song with the line "There was a time when the truth didn't have to be spoken, But now everything's broken". It's easy to think that once upon a time, everyone knew what was good and did it without being reminded. But is it true? When did God start giving humans commands? Before the fall! Be fruitful & multiply, subdue the earth & don't eat from the tree. Even when humans enjoyed the perfect relationship with God, He was still giving them commands.
So let's remember that God did not start giving us commands after the entrance of sin. The Law is not some result of the fall that has no place in God's perfect world. When we finally have a perfect relationship with God in heaven, I suspect that He'll still tell us what to do!
The law is entirely useless at bringing us to salvation, incapable of making us good people. But once we are saved by the work of Jesus and sancified by the Holy Spirit, we will be able follow the law--the commands of God. Jesus said that if we love Him, we will obey His commands. Obeying His commands will not make us able to love Him, but once we love Him, obeying His commands is a normal part of our relationship.
I suspect that none of what I just wrote is news to theologians, and there are probably whole books devoted to the fact that the first laws were given before the fall. But I've never read any of them, so this is my two cents worth.