He did not believe. ("I cannot utter the word 'Lord' with meaning. Because I do not believe that he will come to judge me; because that says nothing to me. And it could say something to me, only if I lived completely differently.") But he tried to imagine what it would be like to believe, and (sometimes at least) he wanted to believe. Here's why:

What inclines even me to believe in Christ's Resurrection? It is as though I play with the thought. -- If he did not rise from the dead, then he decomposed in the grave like any other man. He is dead and decomposed. In that case he is a teacher like any other and can no longer help; and once more we are orphaned and alone. So we have to content ourselves with wisdom and speculation. We are in a sort of hell where we can do nothing but dream, roofed in, as it were, and cut off from heaven. But if I am to be REALLY saved, -- what I need is certainty -- not wisdom, dreams or speculation -- and this certainty is faith. And faith is faith in what is needed by my heart, my soul, not my speculative intelligence. For it is my soul with its passions, as it were with its flesh and blood, that has to be saved, not my abstract mind. Perhaps we can say: Only love can believe the Resurrection. Or: It is love that believes the Resurrection. We might say: Redeeming love believes even in the Resurrection; holds fast even to the Resurrection. What combats doubt is, as it were, redemption. Holding fast to this must be holding fast to that belief. So what that means is: first you must be redeemed and hold on to your redemption (keep hold of your redemption) -- then you will see that you are holding fast to this belief. So this can come about only if you no longer rest your weight on the earth but suspend yourself from heaven. Then everything will be different and it will be 'no wonder' if you can do things that you cannot do now. (A man who is suspended looks the same as one who is standing, but the interplay of forces within him is nevertheless quite different, so that he can act quite differently than can a standing man.)

(from Culture and Value, translated by Peter Winch)