XVII. On God’s knowledge”
Whatever is past no longer exists, and whatever is future does not yet exist.
Both the past and the future, therefore, are entirely absent. To God, however,
nothing is absent, and hence nothing is either past or future, but everything is
present to God.
Augustine, Responses to Miscellaneous Questions XVII. On God’s knowledge
Thanks for this, Ryan Mullins had said most of classical theologians were presentist, i.e., that only the present moment exists. He then does an excellent job of showing how presentism conflicts with timelessness. See his book, The end of the timeless god.