Should we?
Yes. That’s God’s plan for mankind for our benefit.
MUST we? No.
We never could to begin with and it doesn’t or wouldn’t save us if we did.
The commandments are given so that we’d recognize sin. It reveals our failure to live out the first two commandments, the greatest ones that Jesus gave.
If we loved our neighbors as ourselves, we would automatically live them.
The problem is that we humans are capable of obeying the letter of the law without having the heart for it and if everyone did obey the Law, we’d certainly by far have a better life in this world, but could still be as far from God as ever.
If our focus is on law keeping, we’ve taken our eyes off Christ.
I don’t think we should be obsessing over law keeping.
Don’t forget the verdict handed down at the Council at Jerusalem in Acts 15 and their conclusion in the matter.
Acts 15 was concerned with the material things of Mosaic law such as circumcision, meats, washings . . . That law was abolished at the cross.
MUST we? No.
If that were the case then we are free to sin. Feel like some adultery? Indulge your self. See that new purse you've been longing for? Slip it under your coat. How much sin is too much for God?
The problem is that we humans are capable of obeying the letter of the law without having the heart for it
That doesn't sound like a defect in the Law to me.
If our focus is on law keeping, we’ve taken our eyes off Christ.
You make them sound incongruous. They are not. If we love Jesus we will love His Law. The Law is perfect. If you hate the Law you hate God. Matthew 5:48 states "Be ye therefore perfect, even as your Father which is in heaven is perfect." That doesn't sound like the Commandments are optional to me. How much sinning do you think is allowed in Heaven?
To further clarify, the Ten Commandments are not a formula to get to Heaven. I didn’t murder anybody today! Hurrah I’m going to heaven. No, the absence of committing sins means nothing. We could sin in our heart. To follow the Law we must have the Love for God in our hearts. We must yearn to please Him. We must be thankful every waking moment. This burning desire to please God must motivate us or else we fail. The Law without love does us no good. To meditate upon the sacrifice on Calvary every single day and to allow the Holy Spirit to live within us is the only way to live.
Conversely:
If our focus is on Jesus, we’ve can be fairly assured that we'll be keeping the 'law' as best we can.