Why can't the law save you?
The law cannot save because it only addresses outward deeds, not the sin nature called old Adam that keeps producing sin. Covering it up won't work; the root remains, and God sees the internal corruption. No one can approach God on the merit of their own works; righteousness comes by believing God, as Abraham did.
Les explains that the law cannot save because the real problem is old Adam, the sin nature. Using the bootlegging illustration, he notes that outlawing alcohol did not stop people from getting it; authorities had to find and destroy the stills. In the same way, old Adam is like a still that keeps putting out sin. You can try to cover it up or wallpaper over it, but it won't work until you deal with old Adam. By the deeds of the law no one can approach God on the merit of what they have done. God says we can do nothing to merit favor with Him, no matter what denominations or theologians teach. Instead, as Paul says, Abraham believed God, and his believing caused God to call him a righteous man.
Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
More Questions
Why can no one be saved by the law?
No one can be saved or justified by keeping the law, because Paul states that by the deeds of the law no flesh is justified and the law could not bring anyone into salvation.
Why can't a person be justified by the deeds of the law?
Doing the law's deeds cannot justify anyone in God's sight because the law gives knowledge of sin, not knowledge of salvation or a way to heaven.