Believe nothing on faith alone, or on authority.
“Now, Kalamas, don’t go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, ‘This contemplative is our teacher.’ When you know for yourselves that, ‘These qualities are skillful; these qualities are blameless; these qualities are praised by the wise; these qualities, when adopted & carried out, lead to welfare and to happiness’ — then you should enter and remain in them.” (Siddhartha Gautama, Kalama Sutta)
“Believe nothing on the faith of traditions, even though they have been held in honor for many generations, in many places. Do not believe a thing, because many people speak of it. Do not believe on the faith of the sages of the past. Do not believe what you yourselves have imagined, persuading yourself that some god inspires you. Believe nothing on the sole authority of your masters or priests.
After examination, believe what you yourself have tested and found to be rational, and conform your conduct thereto.” (Another rendition from the Kalama Sutta)