At John 8.58, Jesus asserted, "...before Abraham was, I am." This is apparently a declaration of his timelessness. If God (and the Son) exists outside or transcendent of the dimension of time, then their eternity is the reality in which time does not exist. There is no past or future, only the present. Einstein asserted that time is relative (special relativity) in the universe and is dependent on spatial motion - meaning that there is no such thing as absolute time, so from a perspective of absolute truth (reality), time is not a dimension.
Jesus' "I Am" statement declares that He is not past nor future, but His reality is eternal, and therefore, present. His reality transcends time.