The Lightning Thief
"Percy," Chiron said, "you may choose to believe or not, but the fact is that immortal means immortal. Can you imagine that for a moment, never dying? Never fading? Existing, just as you are, for all time?" (5.123)
"Come now, Percy. What you call 'Western civilization.' Do you think it's just an abstract concept? No, it's a living force. A collective consciousness that has burned bright for thousands of years. The gods are part of it. You might even say they are the source of it, or at least, they are tied so tightly to it they couldn't possibly fade, not unless all of Western civilization were obliterated. The fire started in Greece. Then, as you well know—or as I hope you know, since you passed my course—the heart of the fire moved to Rome, and so did the gods. Oh, different names, perhaps—Jupiter for Zeus, Venus for Aphrodite, and so on—but the same forces, the same gods."
"And then they died."
"Died? No. Did the West die? The gods simply moved, to Germany, to France, to Spain, for a while. Wherever the flame was brightest, the gods were there. They spent several centuries in England. All you need to do is look at the architecture. People do not forget the gods. Every place they've ruled, for the past three thousand years, you can see them in paintings, in statues, on the most important buildings. And yes, Percy, they are now in your United States." (5.189-191)
"What's the most common thing gods did in the old stories? They ran around falling in love with humans and having kids with them. Do you think they've changed their habits in the last few millennia?" (7.26)