Necessity implies existence?

While reading up until the chapter 139--counted by Prime numbers--,I encountered a so-called Occam's razor, which is a law:

Entia non sunt multiplicanda praeter necessitatem.

Which is Latin and means:

No more things should be presumed to exist than are absolutely necessary.

Which means only those things that are crucially vital should exist.

If we assume that this law is globally true, then God doesn't exist for those who don't feel he's vital. On the contrary, he does absolutely exist for those who seriously think that he's the one.

Personally, I think that this law is fair enough to let one decide what should exist and what shouldn't depending on one's necessity. In my different point of view, however, this law is rather trivial...