How can you best challenge a delusional belief. There must be something in psych literature on this.?

I am expecting respondents who have little understanding of psychiatry to try to use logic here. Before you answer this question be sure you understand the true nature of a "Delusion." . Delusions are fixed false beliefs. Generally, the more you challenge delusions with logic the more entrenched they become. For example explaining to a delusional person that they are not, say the King of England, by showing them an encyclopedia or other "proof" nearly always results in a more entrenched delusional system.