Fact
A person who understands the scientific method can test to see if the facts of a scientific theory are correct. When statements have been tested and shown to be not false, they may be "true". The facts of each scientific theory have usually been questioned and tested by many people. Because of this, we know that the knowledge of a scientific theory is fact and not opinion. Examples of scientific theories include the theory of relativity and the theory of evolution. More simply, it is a fact that the Earth goes around the Sun (and not vice versa). This took so long to establish because a leading religious body had the reverse opinion (see articles on Galileo and Copernicus for the story). Now we can say that there is a difference between statements of fact, and opinions or claimed truths of religion. The difference is in the way disputes about the truth are decided.