
Pascal once wrote that belief in God is incomprehensible and disbelief in God is inconceivable.
The same can be said about the infinite/eternal, but I think of it in different wording. Imagining something or someone to not have a beginning is difficult to comprehend, but not as difficult to imagine.
Imagining something to not have a beginning or end, might be difficult because of our finite point of reference. Everything we humans observe in this world has a beginning, even the universe (see below). However just because everything we know has a beginning doesn't mean that everything HAS to have one.
Science has confirmed that the universe has a beginning. The logic goes that because of the doppler effect found in cosmic background radiation, we know that space is expanding. If space is expanding, then it must had a starting expansion point.
Science has also confirmed that the universe has an end. Our telescopes find dying stars all the time. Our sun has a very definite lifespan. When the sun goes, life on earth as we know it will cease as well.
This confirmation of the finiteness of the known universe begs the question: "What caused it all?" After all, if the universe were eternal, such a question wouldn't be necessary. But we know that finite things have causes/sources.
I only know of two possibilities. Either an eternal process caused it, or an eternal being.
Belief in an eternal being is a simpler explanation than belief in an eternal process. After all, belief in an eternal being also explains the order found in the universe. Order always comes from intelligence. No exceptions have ever been found.
Something else that Pascal observes is that God has revealed Himself with enough clues in creation to know of His existence, but He also hides Himself enough so that we may sense our unworthiness of Him.
If Creation testifies of this, then this begs the question: What can save us from this condition?

