For the purpose of the following, the word 'One' connotes some innate state of humanity, where all exist as some undifferentiated source of life energy; 'One' may be what the word "God" or any other variation of the term or intellectual understanding seeks to define. 'One' may be I, you, we, or they, but none neither alone nor in part can be 'One'.
In this present state of being, there 'will not' be One—one world, one love, one being. In the state of individuation there 'will' only be what is perceived through One's experience as individual or Self, and as such, many selves. Here there are several worlds. There are my, your, their, and its worlds.
Consider your self a world. Within worlds, there is conflict, and drama being played out. There are 'world wars' (internal conflict) and 'wars of the worlds' (external conflict). A 'world war' has to do with self-trust, self-confidence, self-understanding, self-acceptance or self-conquest. A 'war of the worlds' has to do with the way you interact with everything you regard as distinct from "your" self (e.g. "another" self and its experiences, ideas, or beliefs); it is a war of differentiation & individualization wrought by interpretation, opinion, and disagreement. A 'war of the worlds' is a disposition of Self that is concerned with outer conquest and its sole preeminence. Both are concerned with individual recognition & acceptance. 'World wars' and 'wars of the worlds' are simply valuative dispositions that comprise selves. They are the framework for life as we know it; more specifically, as the One is currently experiencing it.