The Freethinker Motto

We have been camping and hiking in the John Day river area, and we visited a cemetery off the paved road and through several farm gates. A few gravestones had this symbol on them from the 1890's. They were all women's graves and I when we got back to internet land, I looked to see what this may mean. I think I have found my affinity group! Does anyone belong to a Freethinker group? See some explanation here. Strangely I now recall my father, accusing my outlandish notions of the 1970's of being freethinker claptrap. Little did I know I was aligned with the Oregon pioneers!