"who also made us adequate as servants of a new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life." ( 2 Cor 3:6)
One of the main purposes of the law/letter was to be our tutor to Christ...that through the law we would come to know God & enter into a relationship with Him - a relationship free from rules, laws, and living out of our own self-efforts.
It's sad to say, but all too often I meet with what seems like depressed Christians or uptight ones, not joyful ones...what the heck! Christians should be the most joyful people on the planet, as we have been given the greatest gift in being in a relationship with Jesus Christ.
In my opinion, I think a lot of the frustration, difficulty, and lack of joy that some followers of Christ experience is directly related to mixing the old covenant and the new covenant. It has come from trying to live for Jesus, instead of enjoying a relationship with Jesus...'thou shalt not' kind of living (man-initiated), instead of 'thou will' kind of living (God-initiated) - Ex. 20 & Heb. 8. It's freedom to be united with the living God & experience His life being lived through our life.
When I read the Word, I never sense from Paul, John, or any other New Covenant writers that the Christian life was this great struggle and burden to live, rather I see them laying hold of what Jesus said, "my yoke is easy & my burden is light."
I don't believe that anyone can join in with the apostle John and say that His commandments are not burdensome (1 Jn 5:3) unless one experiences living by grace and not by the law...living by the law as a believer will kill us, but living by grace in a relationship with God will give us life.
Jesus' goal for our lives was life & life abundantly...I believe a day is coming soon in the body of Christ where believers will live confidently in their relationship with God as a saint not a sinner, as righteous not unrighteous, as a son not an orphan, as a friend not a slave, and as a lover not a worker.
I was only planning on writing a quote I just read, but forget the quote you just got a rant from me.