Jesus' most famous discourse to the ordinary people of his time is known as the "Sermon on The Mount". In it this (Perfect) Jewish Rabbi living under the Law speaks to people also living under the Law and tells them what the Law really requires of those who seek to live by it. Most people would think that the Law, even as seen by many in it's bare physical essentials, was impossible to keep anyway, but when Jesus shows you the intent God had in giving the Law as a standard, they come to realise that it "really" is impossible to keep!
Now before the giving of the Law at Sinai God's people lived by faith, and under God's grace, but the Israelites were arrogant enough to think that "Whatever God said, they could do!" So God gave them the Law to keep and by that to earn His blessings. Of course they and us could not keep it. All they and we deserve through our self-effort is the penalty (curse) for NOT keeping the Law - disease and death!
And it's not just a few laws which we might choose ourselves that we have to keep perfectly. James tells us that if we break just one of the commands in the whole Law, which has 613 commands, then we are guilty of breaking them ALL!
Jesus Himself went on to show the actual requirement of many of these laws as He continued to teach the crowds in His Sermon on the Mount.
We can look at another small example in Matthew 5:27-28.
It is not just the physical act of adultery which breaks the Law. Jesus points out that if anyone listening to Him or reading His message later had lust in their heart for someone, they were breaking God's Law, and when you break one.....
But the whole idea is for
you to realise that you cannot live righteously of yourself and to see
that you need a saviour. You need someone to die for you; you need
someone to take your punishment for you; you need someone to be buried
and go to hell for you; and you need someone to rise from the dead and
give YOU life! You need the Gospel!
When we understand the concept of the Kingdom of God, that Jesus and Father God live IN the true believer and so the life we live is not ours but it's Jesus who lives His life in and through us, then on accepting Jesus, we will be empowered to live righteously.
We (Christians) are the
righteousness of God. We are to live guided by Holy Spirit 24/7 so that as we
rely on Jesus living His life through us we can be changed by the living word.
"JESUS IS OUR LIGHT"!
Best wishes for Grace and The Peace of Jesus.