Berdyaev was a Marxist and, when writing this work, retained some respect for his old teacher Marx: in fact, he dedicates it to him. Perhaps for that reason, he acknowledges the existence of class struggle, which others deny, such as the bourgeoisie or reactionaries.
Class struggle exists and is caused by capitalism, which is the enemy to be overcome if one also wants to end communism, since the latter could not exist without the former. Communism depends on class struggle and on capitalism as a prerequisite for the proletariat’s conquest of power, and as a sine qua non link to reach that omega point in history, which is the classless society.
Christianity, on the other hand, is incompatible with class struggle, as it is not a religion of confrontation but of concord. The goal of Christian social action would be to put an end to that struggle fostered by capitalism. Christianity, in effect, must take the side of the worker against big capital and the bourgeoisie, which dehumanize man and turn his labor into a commodity.
Thus, we see the echo of the teachings of the popes, although they do not condemn capitalism as a whole but rather its initial vices and its potential drift toward the dehumanization of the worker. It is worth noting that Berdyaev, in his exposition, briefly mentions the sanctification of labor, although he does not develop it further, of course.
He also does not elaborate on what would be his concept of an alternative to capitalism, and although he speaks of socialism with more sympathy than he does of communism, it can be inferred that his ideal would be more like a unionism.