Yes, we largely don't know. But we can know beyond any doubt that we are, and also who we are. All of us can know "I am." And that's basically it as far as knowledge goes. But, surprisingly, that's also enough because it reveals that there's only ever one "I am," which we all are. That's why I said that you can call it selfishness -- all we do, we do to, and for, the same "I" -- it's not, however, the same as egotism.

When you know that, there's no need for religion (I meant the end in literal way as cessation), and hope, despair, nihilism, even suffering, lose their meaning. To paraphrase Bible (Matt. 6:33-34), don't hope or despair about tomorrow, find the kingdom of God here and now, and the rest will come with it.