The Hebrew believers were being tempted to go back—to return to the old system, the Levitical priesthood, the familiar rituals of Judaism. And the author’s message is clear: Why go back to something inferior when you have something infinitely better? Why go back to shadows when the substance has come?
The big Idea of the text is: Because Jesus is a better High Priest, we have a better hope and a better way to draw near to God.