There are literally hundreds of laws found in the Old Testament.  For a person wanting to obey God, this work is actually insurmountable.  For people who have trusted in Christ, this law is still a picture of the holiness of God.  And we have come to accept that we are unable to live up to His perfect standard.  The redeeming part (literally) of it is that Christ has fulfilled all this law for us.  We only trust in Him.

But what many people fail to remember is that without without trusting in Christ, all that law still applies to the individual.  God is still God, even to those who do not acknowledge He exists.  He is not a fairy that lack of belief would cause Him to disappear.  Regardless of individual belief, God is there.  And the fact that He is Holy and Just reminds us that His Holy Law had to be, or will be, fulfilled.

The question for the individual is not whether God will ‘let them off’ because they didn’t know any better.  But the question is how will you fulfill God’s Holy Law?  Jesus knew that to be brought into the family of God, someone would have to fulfill the Law in your place.  That is what He did.  He, being God Himself, left heaven, came to earth and lived a sinless life (fulfilled the Law), and then took the sinners (the one who violated the Law) place by taking the scourges of a rebel and the death of a criminal on a cross.  But because He was sinless, and being God Himself, He rose from the dead and lives.  Death no longer has any affect on him.  Because the wages of sin is death, and He has no sin.

“17 “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. 18 For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished. 19 Therefore whoever relaxes one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever does them and teaches them will be called great in the kingdom of heaven. 20 For I tell you, unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.” – Jesus in Matthew 5:17-20

“the Son of Man came not to be served but to serve, and to give his life as a ransom for many.”
– Jesus in Matthew 20:28

The only one who can fulfill the Law and live, is Jesus.  So who will fulfill the law for you?  Will you pay the price, or will you trust Jesus?