A person who forms opinions about religion on the basis of reason, independently of tradition, authority, or established belief. Freethinkers include atheists, agnostics and rationalists. No one can be a freethinker who demands conformity to a bible, creed, or messiah. To the freethinker, revelation and faith are invalid, and orthodoxy is no guarantee of truth.
Freethinkers are naturalistic.
Truth is the degree to which a statement corresponds with reality. Reality is limited to that which is directly perceivable through our natural senses or indirectly ascertained through the proper use of reason. Reason is a tool of critical thought that limits the truth of a statement according to the strict tests of the scientific method. There is no great mystery to morality. Most freethinkers employ the simple yardsticks of reason and kindness.