Why was it difficult for the United States and Soviet Union to find common ground?

It was difficult for the United States and Soviet Union to find common ground for diplomacy because they held radically different ideologies. The United States valued private sector control of business, private property, and—for the most part—traditional, Protestant Christianity. The Soviet Union, on the other hand, valued government control of business and production, communal property, and materialism/atheism.

These varying, deeply-held beliefs about politics, economics, and religion made it nearly impossible for the United States and Soviet Union to find any common ground. Since the United States represented one ideology many of its citizens believed to be true, a lot of Americans viewed the Soviet's nearly-opposite ideology to be evil, and vice versa.

This lack of common ground also bred suspicion and distrust. The United States, for instance, was incredibly paranoid about a supposed Soviet plot to infiltrate the United States government and make it communist.