What's life's deep secret? Do we ever really understand life? Do we ever really get things right? What lies at the center of life?

These are the deeper questions that gnaw away inside of us and we are never really sure how to answer them. Do we ever really understand what our lives are all about?

Yes and no! I suspect that most of us go through life bouncing back and forth between knowing and not knowing, between feeling steady and feeling insecure, between having days when we feel we're getting things right and having days when everything seems out of sorts.

As the Sufi, mystic Rumi, once put it, we live "with a secret we sometimes know, and then not know."

I suspect we all know what that feels like. Some days, it seems, we know the secret to living and feel we are inside of things, at their heart.

This may not necessarily be something we are consciously aware of, but something sensed at some deeper level. There are times when our lives make sense in a way Vaclav Havel once described. Steadiness, he suggests, lies "not in the conviction that something will turn out well, but in the certainty that something makes sense, regardless of how it turns out." There are days when we know the truth of that.

But there are also days when we aren't sure exactly what we know, when we feel outside of things, when the circle of life seems to exclude us, and we walk round the edges of love and meaning, unsure, unsteady, feeling some inexplicable guilt because we have the sense that somehow we are doing things wrongly and are not where we should be.

And so we live with a secret we sometimes know, and then not. We feel steady and then unsure, strong and then vulnerable, moral and then guilty; loveable and then unworthy; we sense that we know the secret to life and then suddenly we feel we don't. Sometimes we stand inside of things and sometimes we stand outside of them.

I've always been struck by a very poignant expression in the Gospel of Mark. He tells us that Peter betrayed Jesus at his trial, ultimately cursing him in order to save himself. After that betrayal, Mark (in a stunningly cryptic statement) says simply: "Peter went outside!"

Outside of what? Obviously he is referring to much more than Peter simply stepping outside of a door and leaving a room or a courtyard. In betraying Jesus, and in betraying himself, Peter "went outside" of something else, namely, outside all that's best inside of himself, outside of the community of life, and outside the secret of life itself.

And what is the secret of life itself?

In the Gospel of Mark, Jesus says: "To you is given the secret of the Kingdom of God, but to those outside, everything is in riddles." To whom is he referring? Who is "you"? What is the secret? What puts you inside? What puts you outside and makes the Gospel a riddle?

In Mark's Gospel, the answers to these questions are clear: You are "inside" or "outside" the true circle of understanding, not on the basis of being Jew or Gentile, of being man or woman, or of going or not going to church. Rather you are inside or outside the circle of true understanding on the basis of "getting" or "not getting" the secret. And what is the secret?

In essence, the secret to life is the cross of Christ or, as various Scripture scholars and spiritual writers put it, the brokenness of Jesus on the cross, the wisdom of the cross, the invitation that lies inside the cross, and the willingness to live out the demands of the cross.

It's not easy to try to summarize all that this means. To do that, one would have to summarize all the deepest challenges within revelation, theology and spirituality: God's unconditional love and forgiveness, God's loving presence inside of human twistedness, vulnerability as the path to intimacy, God's identification with the poor and the excluded, the necessary connection between suffering and glory, the paradoxical nature of love and life (which can only be received by giving them away), the centrality of self-sacrifice as the key to love and fidelity, and the importance of giving our lives over without resentment (of not sending the bill whenever we carry someone's cross).

There's a lot inside this secret! And when we are at our best, when we let the demands of love, truth and fidelity take us to where we would rather not go, we know its truth and live inside of it. On those days, we know the secret of the kingdom and the Gospels make sense.

But then there are days that, like Peter when he betrayed Jesus, we "go outside," outside of truth and what's best inside of us, and from that perspective life, love, truth, Jesus and the Gospels all look like an empty riddle.

Oblate of Mary Immaculate Father Ronald Rolheiser is a specialist in the field of spirituality and systematic theology. His website is www.ronrolheiser.com.