That last part says it all, the purpose of the law was to enlighten (or endarken(?)) us to sin. We weren't doing a good job on our own. That what is meant in verse 10, as originally read in Psalms, "None is righteous, no, not one; No one understands, no one seeks for God. All have turned aside; together they have become worthless;" This all powerful God laid out this beautiful creation then placed man among everything. You think He was a little ticked when disobedience sprouted from our will? Adam and Eve, Sodom and Gomorrah, Tower of Babel, Noah... He had to do something. Hello law.
This law was never meant to me a determining factor in salvation. We were in a perfect relationship with God, for a few days, the "The Fall of Man".... God's been trying to lead us back to that relationship ever since but we (I) keep trying to do it ourself and we can't. It's like this....screw up (sin), punishment (law), forgiveness (for a season), screw up (sin), punishment (law), forgiveness (for a season), screw up (sin), punishment (law), forgiveness (for a season).... get it? The law pointed to the sin which pointed to our complete inability to conquer it on our own. That was and is it's purpose. God doesn't want me to follow a set list of rules to be saved, he wants me to come to Him because I love Him, can't live without Him and want to get back to that perfect relationship one day.
(sorry if that doesn't make any sense, I get thoughts and know what I mean but sometimes maybe can't spit it out right. I guess it only matters ultimately if I get it but if you have any questions let me know)
Father I get it, I can't live up to your righteousness, my only chance is to be washed in the Blood of the Lamb.