Re Bob Mathiesen's note: I checked umertvit'/umershchvljat' in the 17-volume dictionary and Evgen'eva, where it has no stylistic mark at all (and lots of clearly non-ChSl examples in the 17-volume dictionary), and in Ushakov, where it is only marked as "knizhn." Sounds to me like high-style Russian, not Church Slavonic.