If people are to be defined by what they do not believe, than should we for instance define Christians as non-Muslims? Just because someone does not believe in one particular "ism" that does not mean they do not believe in ANYTHING.
An ism isn't made an ism because it has a God as a focal point. It is an ism because it is enough of a unified ideology that more than one person can get underneath its tent. Deists don't have any right to define the secular ideologies which other people find meaning in, any more than secularists get to define anyone else's God.
Your question is hollow - it has no spirit