God’s decretive will [also called His hidden, sovereign or efficacious will] refers to the secret, all-encompassing divine purpose according to which He foreordains whatsoever comes to pass. His preceptive will refers to the commands and prohibitions in Scripture. One must reckon with the fact that God may decree what He has forbidden. That is to say, His decretive will may have ordained that event x shall occur, whereas Scripture, God’s preceptive will [also called His revealed or moral will], orders that event x should not occur.
Sam Storms