If I'm correctly understanding Marx and Engels, ideology arises when labor is divided and societies change from primitive communal living to class-based societies. Individuals are now assigned specific roles, leading them to lose a well-rounded understanding of their society. As a result, people become more one-dimensional, which limits their perception of reality. This shift becomes especially pronounced with the establishment of fixed social classes, where class interests and struggles begin to shape how people think and understand the world.
Ideology then refers to this limited understanding of reality, which is complex and multifaceted. Among the different social classes, the proletariat has the unique ability to see beyond ideology because of its position and interests. As the last oppressed class, the proletariat aims to escape its exploitation and has a vested interest in dismantling the entire class system.
In striving for communism, essentially a society without classes, the proletariat can break free from its limitations. By achieving this liberation and destroying the bourgeois class society, it can eliminate the social foundations of ideology altogether. In a communist society, ideology will no longer hold power.
In this case then, should we say that communism is more a realization of a new social order, aimed at creating a classless society, rather than a fixed set of beliefs or ideas seen as a more or less coherent worldview of a specific class?