Upvote:3
There is no biblical basis for the claim that the Ten Commandments are arranged in order of importance, and to my knowledge, there is no Roman Catholic teaching on the subject either. There are a couple places where Jesus does provide us with some insight into the degree of importance of the various commandments, but one stands out. Matthew 22:37.
It is important to notice that Jesus is not citing the Ten Commandments when he is discussing the two greatest commandments. The two greatest commandments are:
The first two commandments of the Ten Commandments are
Jesus considers the two "Greatest" commandments to be a summary of all of the commandments.
If anything, the Luke 18:18 passage suggests that the Ten Commandments are not all in order of importance, since he freely rearranges them however he wishes.