I have a non-Christian friend who asked me to explain how it is that God did not have a beginning. I could not explain this challenging aspect of the Christian faith.
Would you kindly explain this for me to pass on to him?
Your friend asks a metaphysical question, which is best answered by St. Thomas Aquinas in his “Summa Theologica,” Part I, Article 10, on eternity. Let me see if I can summarize the argument.
Not only did God not have a beginning, he will have no end, because God is eternal. Your non-Christian friend will have difficulty understanding this just as Christians have difficulty understanding this, because the nature of God is far beyond anything we can relate to. The question of God’s existence, without a beginning and without an end, is not a specifically Christian issue.
It is largely a philosophical issue. The very nature of God is to exist. God has other attributes as well, many of which can be deduced by reasoning: God is eternal, immutable, omniscient and omnipotent.
Just for fun, try to wrap your mind around this explanation of eternity by the Angelic Doctor. (Warning! Pay very close attention.)
I answer that, As we attain to the knowledge of simple things by way of compound things, so must we reach to the knowledge of eternity by means of time, which is nothing but the numbering of movement by "before" and "after." For since succession occurs in every movement, and one part comes after another, the fact that we reckon before and after in movement, makes us apprehend time, which is nothing else but the measure of before and after in movement. Now in a thing bereft of movement, which is always the same, there is no before or after. As therefore the idea of time consists in the numbering of before and after in movement; so likewise in the apprehension of the uniformity of what is outside of movement, consists the idea of eternity.
Further, those things are said to be measured by time which have a beginning and an end in time, because in everything which is moved there is a beginning, and there is an end. But as whatever is wholly immutable can have no succession, so it has no beginning, and no end.
Thus eternity is known from two sources: first, because what is eternal is interminable--that is, has no beginning nor end (that is, no term either way); secondly, because eternity has no succession, being simultaneously whole.
Rev. Francis J. Hoffman, JCD (Fr. Rocky) is Executive Director of Relevant Radio. Ordained as a priest for Opus Dei in 1992 by Blessed John Paul II, he holds a doctorate in Canon Law from the Pontifical University of the Holy Cross, an MBA from the University of Notre Dame, and a BA in History from Northwestern University. His Question and Answer column appears in several Catholic newspapers and magazines across the country.