Different people have different experiences in which shape their opinion about god. We have the believer and the disbelievers. Flew is one of the disbelievers who tries to prove the fantasy of god. He successfully questions theory of god by using the Verificationist Theory of Meaning, the gardener parable, picture preference, the problem of evil, and statements about god. .
There are great deal of hypothetical statements the trick is to know how to distinguish between a false meaning and a confirmed one. The method that is used to verify and falsify meanings of statement is the Verificationist Theory of Meaning. We as a society use this type of technique to differentiate between what is true and what is phony in a declarative statement. For instant if one would to say "I am holding a book in my hand". The meaning of this statement can either be verified or falsified by the Verification Theory. One can verify the meaning of this statement by saying that there is actually the book in that person hand. Therefore the meaning of that statement would be true because one can prove the proclamation to be correct by seeing that there is actually a book in that person's hand. A false statement would be the one that the meaning cannot be proven. For example everything we know is going to change in the future. This meaning of statement cannot be proven because nobody was affected by it. Therefore this meaning of statement would be considered to be false. We can use this method to distinguish between true and false meanings of statements one makes.
Flew uses the garden parable theory to question the existence of god. According to Flew in the garden parable two men stumbled into a jungle. In the jungle they saw many flowers and weeds. One explores assumed that someone planed the flowers, the other one disagreed. So they spend the night to see if the gardener would show up but he never did. Than they barbed wired and electrified the fence and set the bloodhounds to patrol the space yet still there was nothing.