Something which non-believers can never understand is the positive feeling belief in God and religious observance can bring one.
Without God we are really alone in the universe. "Here today, gone tomorrow, that's me!" (Pink Floyd - Dark Side of the Moon).
Without Torah we don't really know what God wants of us. So we invent things, generally things we want and say that it's God's will that we be happy and since these things make us happy, well that's what God wants of us. But all these thrills are cheap and temporary, fun at first but lacking in novelty and enjoyment after a while.
With God and Torah, each day is a new, positive challenge. How can I enhance my neshama today? How can I fulfill His will today? How can I make the world a better place today?
Where are the objective answers? In Torah. Where can I find eternal values? In Torah.
Purim is perhaps the best example of the divide between right (us) and wrong (them). Although God's name never once appears in the story of Esther, it doesn't have to. The believer knows through his faith that God arranged events the way they did. As a result, not only do we have a great story and a good reason to drink heavily, but we can also derive moral lessons and grow as individuals and a people as a result.
For the non-believers? Well first of all, the story probably dind't happen, and even if it didn, it didn't happen like that and God, if He's around at all, chas v'shalom, had nothing to do with it. And it might be a great story but there's nothing they're going to learn from it. Garbage in = garbage out.
Tonight we will be in the positive, full of love and gratitude to God Almighty and by tomorrow we'll be that much more complete. And them? They'll still be mierable, basing their entire lives on negating all that's great about ours. Oh well, sucks to be them.