First, theoretical practice is the fundamental driving force for the end of German idealism philosophy and Feuerbach materialism.
As we all know, Hegel's grand theoretical system of "absolute spirit" and dialectical thinking theory that can penetrate everything have undoubtedly been influenced by various philosophical masters in German history, such as Kant. It can be said that "hegelianism" is still formed on the basis of critically inheriting the previous philosophical theories. There is no need to discuss more criticism or inheritance here, but to explore the historical track of the development of philosophical theory from here. Undoubtedly, the sublation and renewal of philosophical theories created by theoretical practice have been highlighted in the process of the emergence of "hegelianism". This sublated fate still holds true in hegelianism. It is only because of Hegel's encyclopedic knowledge system that Hegel's theory is more profound and broad, so that people mistakenly think that "hegelianism" is the ultimate philosophy.
But it is precisely because of this profundity and extensiveness that it provides a broader soil for the later theoretical practice. As Engels said: "Hegel's whole theory has left a broad space for accommodating a variety of extremely different practical views." In Germany at that time, the ideological struggle and theoretical practice between political parties had to involve religious and political fields.
Hegel once called Christianity "absolute" and "perfect" religion. "He thinks that the contents of philosophy and religion are the same. The only difference is that philosophy clarifies what religion understands through imagination and image." But it is precisely because of the existence of dialectical method in hegelianism that some people did not choose to focus on Hegel's religious philosophy system, but fell in love with a more radical way of thinking. As a result, the conservatives and radicals mentioned above appeared. Although Hegel seemed to be more conservative before his death, because "he spent much more on the system than on the method." However, the representative of the radical school came from Hegel's disciple, the so-called "young hegelians". This seemingly puzzling but actually very logical phenomenon shows people that only by deeply understanding and grasping a theory can we see its advantages and disadvantages more clearly and realize the reform and renewal of the theory. It is precisely because of the friction and even struggle between hegelianism's "left wing" and "right wing" in theory and practice that the branch of German philosophy becomes clearer. Of course, here, we can't ignore the aphrodisiac effect of the change of historical wheel on the practice of German philosophical theory. As Engels mentioned in "The End of ludwig feuerbach and German Classical Philosophy": "By 1840, with Friedrich William IV's accession to the throne, people will inevitably stand on one side or another."
With the intensification of the struggle between philosophical factions, "young hegelians" has also been divided, and a large number of the most determined young hegelians turned to Britain and France for materialism based on the need of anti-religion. There is no doubt that there is a conflict with the fundamental system of their school, which makes them suffer between materialism and Hegel's "absolute concept" until Feuerbach's "The Essence of Christianity" is published. Since then, "the magic has been broken and the' system' has been thrown aside."
Second, production practice is the basic condition for the end of German idealism philosophy and the subsequent emergence of Feuerbach materialism.
Engels pointed out the great practical significance of production practice to materialism in The End of ludwig feuerbach and German Classical Philosophy. He said: "In the long period from Descartes to Hegel, from Hobbes to Feuerbach, it is by no means the power of pure thought that pushes philosophers forward, just as they imagined. On the contrary, what really pushes them forward is mainly the powerful and increasingly rapid progress of natural science and industry. "
It is not difficult to draw a conclusion that the production of every scientific theory serves the social production practice, and production practice is often the basic point for the production and development of the theory. Practice tests the truth of the theory and corrects the thinker's ideological system and way of thinking.
From this point of view, Feuerbach's materialism was quickly recognized by people as soon as it appeared, thus leaving an idealistic ideological system that has long occupied the German ideological circle, largely because Feuerbach's materialism is more in line with the requirements of production practice, that is, the requirements of science and technology and production industry. As Engels said: "The most convincing refutation of these and all other philosophical paradoxes is practice, that is, experiment and industry."
To sum up, the emergence of Feuerbach materialism is attributed to the unity of practice in the field of German theory and production, which is inevitable and inevitable in the process of historical creation of human society. This also proves the rationality and inevitability of Feuerbach materialism in Germany, where idealism has long dominated. Of course, it is undeniable that when Feuerbach used materialism to break Hegel's system, he simply put it aside and had the limitations of critical inheritance. However, in the practice of human survival and development, there will also be latecomers who break or supplement their own theories and complete further substitution and development.