I Think It's A Sin

A phrase common in the south and/or bible belt region of the US. Typically means that an action or attitude is negative or not a very healthy state of mind/body that isn't actually condemned in the bible (nor endorsed by it either).

Billy Joe: "Man y'all know I cant come visit you in Mississippi, I've got work all week"

Bobby Sue: "All y'all working is gonna put you in the grave and all your free time is spent at home and I think it's a sin"