The unity of the Decalogue
The Decalogue forms a coherent whole. Each "word" refers to each of the others and to all of them; they reciprocally condition one another. The two tables shed light on one another; they form an organic unity.
To transgress one commandment is to infringe all the others. One cannot honor another person without blessing God his Creator. One cannot adore God without loving all men, his creatures. The Decalogue brings man's religious and social life into unity.
Source: Catechism of the Catholic Church (Vatican.va)