Why, would you be insulted by that?
Not in the slightest.
I am insulted but being charaterized as someone whose thinking is not free. Are Athiest insulted to be called someone that does not believe?
The word freethinker has been in use since the 17th century. Its definition, from dictionary.com:
a person who forms opinions on the basis of reason, independent of authority or tradition, esp. a person whose religious opinions differ from established belief.
—Synonyms: skeptic, agnostic; atheist.
An overview of freethought, from Wikipedia:
Freethought holds that individuals should neither accept nor reject ideas proposed as truth without recourse to knowledge and reason. Thus, freethinkers strive to build their beliefs on the basis of facts, scientific inquiry, and logical principles, independent of any factual/logical fallacies or intellectually-limiting effects of authority, cognitive bias, conventional wisdom, popular culture, prejudice, sectarianism, tradition, urban legend, and all other dogmatic or otherwise fallacious principles. As such, when applied to religion, the philosophy of freethought holds that, given presently-known facts, established scientific theories, and logical principles, there is insufficient evidence to support the existence of supernatural phenomena.
It's a very specific term. It thus characterizes people who aren't freethinkers as having a worldview which is not free of such things as belief in the supernatural...not thought which is not free in general.
The word is much like "La Raza" ~ best abandoned for the sake of comity.