Sentence:  Faith, faith is an island in the setting sun / But <WSD>proof</WSD>, yes / <WSD>Proof</WSD> is the bottom line for everyone 
Meaning of the word marked with <WSD> tags:  The degree of evidence which convinces the mind of any truth or fact, and produces belief; a test by facts or arguments which induce, or tend to induce, certainty of the judgment; conclusive evidence; demonstration.