It is, of course, very difficult to know what the actual causes of human actions are. However, you can certainly make a case that ideology played more of a role than the previous answer gives it credit for.
It is true that both the US and the USSR tried to expand their spheres of influence. However, that does not prove that a desire for resources was their goal. In addition, it does not explain why they came into such great conflict over their attempts to expand.
I would argue that the Cold War was caused largely by ideology. My evidence is this: when countries try to expand their influence, they do not always come into conflict. The US did not come into conflict with England, for example, as it expanded to take Hawaii or when it took Puerto Rico and the Philippines and Guam later on. So why was there conflict between the US and the USSR?
The answer is ideology. The US and USSR did not trust one another because of their respective ideologies. Therefore, when each side tried to expand, the other felt threatened. Because their ideologies were opposed to one another, they saw each other as enemies and each side thought that it would be harmed by any expansion by the other side.
The Cold War encompassed, and nearly engulfed the world for the latter half of the 20th century, roughly the 50 odd years from the end of World War II until the 1980's. The two functional powers left after the devastation of the Second World War where the United States and the Soviet Union. However, during the war, at the Potsdam Conference, the Allies became suspicious of the Soviet Union's motives beyond the common cause of defeating Germany; their suspicions were confirmed in the following years when extended their totalitarian regime throughout Eastern Europe.
Ideologies of government and economics of course were in conflict during this era, but both powers attempted to expand their "Spheres of Influence" across the globe, incorporating the remains of the European post-colonial world. As much as people like to argue that it was an ideological struggle, both powers were really contending for the world's natural resources; the ideology might only reflect how they would use them once they possessed them.