Last night I watched a little bit of It's the Great Pumpkin, Charlie Brown, before being called away to solve an equipment crisis in the sacristy. Any praying person has to identify a little with poor Linus, as his primitive belief in the Great Pumpkin, though doomed and ultimately inadequate, has some elements of theological sophistication.
First, he knows that the Great Pumpkin will not appear if he is dismissed or disbelieved. He requires sincerity and faith, just like the God for Whom believing is seeing. And one only has to peruse the gospel according to John lightly to see that this is indeed the case; to believe and to see God are ultimately the same thing. Meister Eckhart knew this when he famously said, "the eye with which I see God is the same eye with which God sees me."
Second, Linus knows that the Great Pumpkin is not just a fulfiller of selfish human wishes. Unlike Santa Claus, he does not take requests. He brings you something, yes, but you can't choose it and are only called to be grateful.
Third, Linus knows that, despite the failure of the Great Pumpkin to appear, or better, our failure to allow him to appear, Linus must remain faithful.