Human beings are not robots, hominids, holons, aggregates of psychic matter, or any other such conception. They are tripartite beings consisting of mind, body, and soul, which means that human beings are souls embedded within flesh and their brains are the means by which the soul (inner person) interfaces with the world. This means that 'thought' does not originate in the brain but in the unseen realm where hostile ancient spirits exist who can and do drop ideas into the minds of men like yourself.
All of this means that just as life comes from the living Holy Triune God (even Karl Marx grudgingly admitted this), so too does the ability to think come Him. Thus there is no such thing as 'free thinkers' but people who in their hubris deceive themselves into believing they are.