The ideology is how they justify their actions. It is not what causes their actions. The vast majority of people of every ideology do not become terrorists. Ideology is therefore not the issue. To understands what makes terrorists, we have to look at something other than ideology.Who said ideology "makes" people do things? The fact that an ideology would play into their personal calculations would not trump the fact that they were still free acting individuals who chose that course of action. But, it would be equally foolish to suggest that an individuals underlying world view would have no influence on those calculations, either.