"The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one"

This quote by George Bernard Shaw is a tip that happiness is not a reliable procedure of reality. Just because someone is happier thinking something than not believing it, does not always make it true. Shaw is comparing the joy of a follower to that of a skeptic, and comparing it to the joy of an intoxicated male compared to a sober one. He is recommending that the joy of the believer is not a reputable indicator of the fact of their beliefs, simply as the happiness of a drunken man is not a reputable sign of the fact of his beliefs. Shaw is stressing that fact ought to be determined by realities and proof, not by how delighted someone is. He is warning against enabling feeling to cloud our judgement and lead us to think something that is not true.