A SUGGESTION in a Peking editorial that some of Marx's ideas are not really relevant a century later has caught the attention of students of the dialectic around the world. In the West there is open satisfaction that the Chinese are moving forward on a reform that borrows heavily from the free-enterprise model. In the communist East there is, under the surface, shock that the People's Republic of China is trimming its ties to its ideological source, and apprehension about what it may mean for Soviet bloc regimes.

The editorial in People's Daily on Dec. 7 was in the familiar open, candid style that has marked Deng Xiaoping's effort to loosen deadly central controls on the economy and provide new spurs to individual and local initiative. The catchy element in "Theory and Practice" was the explicit observation that Marx and Engels and Lenin were creatures of their times, which have changed. "The economy is a large ocean where many problems are not explained," the editorial said. "It is necessary to read books . . . but it is possible to read too many books. . . . To study and solve economic problems, it is necessary to immerse oneself in the economy and reforms."

Warnings of the "spiritual pollution" resulting from doses of capitalism continue to well up in Peking. The status and outlook of many Chinese are assaulted by the new creed. It is to answer them that the reformers suggest that the gods in the communist pantheon were, after all, mortal creatures. The battle goes on, and its outcome is still in doubt.

Its sights and smells, however, are closely noted in other Marxist bastions. Westerners may find these ideological tilts so much paper war. Those who live in communist regimes know better: they know that the claim of communist parties to rule is that they are the single valid interpreters of the Marxist scripture. If the scripture is openly acknowledged as wrong or irrelevant, then how can a party continue to claim a political monopoly?

China is moving openly toward an answer that some East Europeans have moved toward discreetly: to improve the lives of the people, at least in the economic sphere. There is still no room for political choice in China, it must be noted. The Soviets, however, have yet to grant that a communist party, to rule, must at least serve the people's economic interests. Confounding all of Marx's cheerful forecasts of the withering away of the state, the Soviet party still rules essentially by force. Its unfolding to Chinese progress, or lack of progress, will be a whole new study in the theory and practice of Marxism.