The Greek noun diastole means a distinction, difference, or separation between things. It refers to the recognized or established difference between two categories or realities.
Paul uses diastole in Romans 3:22 and 10:12 to make a revolutionary theological point: 'There is no difference (diastole)' — between Jew and Gentile before God. Both are equally under sin and equally recipients of grace through faith in Christ. The same word that music theory borrows for the rhythmic separation of notes Paul uses to collapse the central division of the ancient world. The Gospel abolishes the ultimate diastole.