1 (in Christianity and other monotheistic religions) the creator and ruler of the universe and source of all moral authority; the supreme being.
2 (god)(in certain other religions) a superhuman being or spirit worshipped as having power over nature or human fortunes; a deity:a moon godthe Hindu god Vishnu
an image, animal, or other object worshipped as divine or symbolizing a god.
used as a conventional personification of fate:he dialled the number and, the gods relenting, got through at once
That's from the Oxford dictionary, producers of the world's most trusted dictionaries... but they would say that See 1 and 2 for the type of God that atheists, to whom Brain was putting his ''challenge'' to, reject and deny.
Opinions, opinions. They're just like bungholes, everyone has one and I'm not interested in yours.
Likewise, you opinionated, mystical bunghole you