Is God willing to prevent evil, but not able? Then he is not all-powerful.
Is he able, but not willing? Then he is malevolent.
Is he both able and willing? Then whence cometh evil?
Is he neither able nor willing? Then why call him God?
God also exists – subsists, perhaps? – as a feeling, as the experiences of thinking and of conscience – whether these come from the otherwise fanciful pneuma deduced by the Stoics, or from some sort of organic neural feedback, or from whatever. We (at least most of us) carry these and participate in them, and we get the feeling that – well – there's something going on that’s not just material. We can call it soul, pneuma, Daimon, Guardian Angel, Christ-in-us, Reason, moral sense, or even numina that lace the land about us. This God cannot be seen, cannot be proven to be material, remains both hard to pin down but also remains self-evident to us.
Whether you claim a Single God (combining all divine attributes), or Two Gods (as I have crudely laid out above), or Three Gods (as in the Christian Trinity, united as One), or a full Pantheon (as in the many and endlessly various Pagan traditions), what we do know is that we are, for the most part, dealing with an Idea whose manifestation is both our whole physical world – the "works" of God – and also our own inner selves. But there’s no other hard evidence, just "hearsay", as Thomas Paine put it. And this evidence that we do have available – that we and the world ARE -- does not have a simple, intelligible signature that quiets all controversy. It is much more complex than that.
The only honest notion about God or the Gods, I am convinced, is the Agnostic One – as in, "I don’t know, but I think … !" The actions of worship (on one hand) and reasoning (on the other) are both indications of God, in us, at work.
* The only authority for this being Epicurus's argument is Lactantius, the only ancient source to quote it. He may have been wrong about having Epicure as the author; in fact, Epicurus's notions of the Gods seem to run counter to the notions inherent in the quote.