What is "epic", anyway? The word is overused in modern culture, and it's losing its meaning. A general definition might be "world-changing", or simply "great, majestic".
Here's where it gets interesting. What is "world-changing"? What is majesty? They imply that something matters, that it has import, that it made a difference. When we look at the universe as a whole, though, what can people do to make a difference? The universe will die, no matter what we do. Can we change that? We can, perhaps, feel better about ourselves by doing something considered "world-changing", and fool ourselves into thinking it really made a difference. But it didn't.
The irony is that the dumbing-down of the word epic more truly reflects humanity's power to be epic. Nevertheless, there is that which is truly epic.
What can make a difference in the outcome of the universe? Only Incorruption. What is the only thing that matters? That which is stronger than death. And that thing, that holy thing, is God. Holiness, Incorruptible, Majesty, Greatness, and Epic: all these words find their true meaning in God.
And here's where words fail me. The epicness of God is always visible, hidden, perhaps, behind the busyness and corruption of the world, but it's there all the same. The epic God is visible in history, and in the future, and in the here and now: he which is, and which was, and which is to come, the Almighty. The world may seem ordinary and tawdry, but behind it all and through it all I can see a taste of the Real, and there's nothing like that. In the natural world, and in the accounts of what God did long ago, and in what he will do, there lives a quiet glory. It's the real magic, powerful and sweet and good. It's the taste of Him.
I just can't describe it. But the best stories have that epic quantity in them, however undefinable it may be.