To what extent was ideology the most important cause of WW2?

A good way of answering this question is by examining the various ideologies that played a role in WW2 and the ways in which they brought about conflict. The key ideological battles to be analysed are those between Fascism and Democratic Liberalism (having particular relevance for the outbreak of war in 1939), as well as that between Fascism and Communism (which was epitomised by the Battle of Stalingrad (1942-43)) which was particularly significant after the Nazi-Soviet Pact ceased in 1941. These two ideas- examining the relative significance of each ideological conflict in bringing about the global war- may form the first two paragraphs of an essay, whilst the argument that ideology was not important in bringing about the war, and that it was in fact down to other factors (such as the weakness of the League of Nations and the policy of Appeasement, or the domestic factors for Hitler in Germany of keeping his citizens happy). The relative merits of each argument ought to be analysed, noting counter-points to each (ideally quoting historians within the answer, such as using Klaus Hildebrad's view of Hitler's 'Stufenplan' to undermine the idea that the conflict was driven by Nazi ideology).