Related quotes
“A saint is a sinner who loves; it's that simple!”
Attributed to Catherine Doherty in Inflamed by Love by Jean Fox
Attributed

“I’d rather laugh with the sinners than cry with the saints, the sinners are much more fun.”
Variant: I'd rather laugh with the sinners than cry with the saints.

"Un Nouveau théologien" (1911)
Basic Verities, Prose and Poetry (1943)

“There is no saint without a past, no sinner without a future.”
This is sometimes attributed to Augustine, but the earliest known occurrence is in Persian Rosary (c. 1929) by Ahmad Sohrab (PDF) http://magshare.net/narchive/NArchive/Misc/Raw_Data/A_Persian_Rosary_by_Mirza_Ahmad_Sohrab.pdf, which probably originates as a paraphrase of a statement in Oscar Wilde's 1893 play A Woman of No Importance: "The only difference between the saint and the sinner is that every saint has a past and every sinner has a future."
Misattributed

“Every saint has a past, and every sinner has a future.”

“Many of the insights of the saint stem from his experience as a sinner.”

“Every saint has a past. Every sinner has a future.”