Why does the Holy Spirit convict men by the Law?
The Holy Spirit convicts men by the Law to reveal their need, because fallen people cannot do it on their own. The Law exposes that their root problem is not merely what they do but who they are, sons of Adam, and that self-reform is useless until God does what only God can do.
Les teaches that the Holy Spirit is moving upon the population and convicting men by the Law of their need of something, because they cannot do it on their own. Paul lays it out plainly, especially in Romans and Ephesians: our root problem is not what we are doing but who we are—sons of Adam. Every baby born into the world is in the same place Adam was after he fell, with a sin-bent personality. That personality may try to clean itself up, but until God does what only God can do, it is all for nothing.