One who sneers at the aims and beliefs of his fellow men?

One who sneers at the aims and beliefs of his fellow men can be described as a cynic or a skeptic. This individual often displays contempt or disdain for others' values and aspirations, viewing them as misguided or naïve. Such a perspective may stem from personal disillusionment or a desire to elevate their own beliefs above those of others. Ultimately, this attitude can create barriers to understanding and empathy in social interactions.