Ontology of created being developed in Christianity let us expose one important aspect of the problem of time. This aspect consists in the necessity of ontological differentiation between time-nature and time-extension(often called diastema). Time in its nature is often associated with changes, but only in the Christianity we can find the metaphysical basis of these changes that is the nature of created things themselves (see: St. Athanasius the Great, Or. contr. gent. 41). Taking it into consideration we have to conclude that ontologically time-extension can't be entirely considered as the simple result of nonidentity of existing things, as some instability, some unfolding of time-nature. For their preservation in being things owe to the Creator, not to their own nature. As there's nothing eternal in created being in the true sense, extensionturns out to be connected with the ontological realm of the Creator. Speaking about the solution of the problem of the substantiation oftime-extension by different Christian authors at least two principal ways can be marked out. The first one can be found with Cappadocians. God could have created everything at once, but He did it in parts and in certain order which is to reveal to man the Creator's Wisdom through examining the creations. It is the time that reveals such order. The second way was developed by St. Maximus the Confessor. From his point of view movement is the integral property of created being which, for this reason, is also under time that is extension (diastema).