Reading how Christ completed our world first, then what Christ completed is reading it backward, and it mixes people up. These same people wouldn't think of reading the last chapter of a book first, or skipping grade school because High School is more important.
The ideal way is to read the Old Testament, with an instructor who can relate each teaching to how Christ completed each thing as you read. I was lucky enough to find just such a man. He had devoted eight years to advanced study, just to be able to do this.
All the people who God gave us New Testament Scripture through had first learned all about the world in the Old Testament, so when they learned what Christ changed they knew what He changed, and how. Those people it was written to also had this background. Most people now spent their time learning about the new covenant first, so it takes a long time to see about an old covenant that, they feel, is best left entirely behind. They hear that OT said to kill animals for their blood, that the Old Testament talks of stoning people, that they were so dumb they thought statues were Gods, and all the law told them were things like not to steal from each other. Besides, some people spent 40 entire years roaming in the desert. Makes no sense to them. Yet, until they learn why and how of these things, the NT truths make no sense. Many posters express conclusions that are far from what God intended, simply out of ignorance.
The fact of the matter is that until you know how the world was and what exactly was changed, you really don't know Christ.