So in regards to the following, you are partially correct, your error is not recognizing the "Change" in the Priesthood and the "works of the Law" pertaining to it.
"All who rely on observing the Law are under a curse, for it is written; 'cursed is everyone who does not continue to do everything written in the book of the Law'. Clearly, no one is justified before God by the Law, because the righteous shall live by faith" (Galatians 3:10-11)
By faith. Not faith and the Law - or any part of the Law. And you can't get away with only observing parts of the Law. If you insist on adding it, scripture says you must do everything written in the Law.
You are one of the foolish mentioned in Galatians 3:2-3; "Did you receive the Spirit by observing the Law, or by believing what you heard? Are you so foolish? After beginning with the Spirit, are you now trying to attain your goal by human effort?"
You have alienated yourself from Christ; "You who are trying to be justified by Law have been alienated from Christ; you have fallen from grace." (Galatians 5:4)
We are DEAD to the Law! "But now, by dying to what once bound us, we have been released from the Law, so that we serve in the new way of the Spirit, and not in the old way of the written code." (Romans 7:4,6)
Jesus has made the old covenant obsolete (Hebrews 8:23) because the Law is not made for the righteous (1 Timothy 1:9) which is what we are (Romans 3:22).