Chesteron said (paraphrased) that the reason truth is stranger than fiction is because people make up fiction, but God is the author of truth.
In a secular culture, because we are shaped more than we know by “fictional thinking” God’s truth often seems strange and even disturbing to us.
‘Do you believe that truth is stranger than fiction?’ ‘Truth must of necessity be stranger than fiction,’ said Basil placidly. ‘For fiction is the creation of the human mind, and therefore congenial to it.’ [1905 G. K. Chesterton Club of Queer Trades 133]
“It is the business of the author to uncover the strangeness of truth.” Flannery O’Connor,
Jill Carentin has an excellent article about this subject on the RZIM website. Click here to read it. . . It would be worth your visit if you did nothing other than reflect on the Flannery O’Connor quote.