1. I can’t see God.
I can’t prove God exists. I can infer that God exists because of the grandeur of the universe, but an atheist looks at the vastness of the universe and sees a cold, harsh place that doesn’t seem to point to a personal God.
I can appeal perhaps to personal religious experiences which have been formative for me, but when I look at many of those experiences, while they were personally encouraging to me, they could be as open to interpretation as the ending ofPan’s Labyrinth. (Was she crazy or did she see something? Who knows).
I can appeal to the miracles that friends of mine claim to have performed/seen–but am I unspiritual to wonder if they’re exaggerating?
Even if they were, I can understand the incredulity of someone listening to a third person account of such an event.
The biblical writers seem to ponder the invisible nature of God (warnings against idolatry, Paul’s comments in 2 Corinthians 4:18, Hebrews 11:1, etc.), but is that enough when you’re trying to have meaningful conversation about God with friends who only trust the scientific method (which evaluates the physical seen world)?
2. The universe is harsh.
Evil, pain, and suffering exist in the world, and if you buy into theistic evolution and an old earth (disclaimer: I do), then you’re left with the problem that for 100,000 years before Abraham, people were dying at 25 of hunger, disease, and brutality.
Does this point to a loving and benevolent God?
The Hebrews had a couple of different ways of processing evil in the world.
One way was proverbial wisdom (if you do right things, life goes well. If you do bad things, not so much).
Another way of dealing with evil was contemplative wisdom.
Contemplative wisdom acknowledges life as it actually is.
It readily admits that sometimes, no matter how many right things you do, good people still suffer.
Ecclesiastes pretty much says, “None of this makes sense. Obey God anyway.”
Job concludes, “Good people suffer. If God’s real, then shut your mouth.”
This can help one to see that the Bible (thankfully) offers no pat answers to the problem of evil, but it can leave a person dissatisfied.