For me a big example is Henri Poincaré.
The French mathematician and natural philosopher (29 April 1854 – 17 July 1912) did important contribution to math, especially to chaos theory.
Apart from that he was a great free thinker.
Thinking must never submit itself, neither to a dogma, nor to a party, nor to a passion, nor to an interest, nor to a preconceived idea, nor to whatever it may be, if not to facts themselves, because, for it, to submit would be to cease to be.
This quote influenced me a lot and for me should be key in everybody life.
Start from proven facts and build your own logic from there. Don't take things without understanding because somebody says so
If somebody could prove religion to me within these boundaries I'm open to it. But quite a challenge :)