Christian Cynic - Oxymoron?

Is it possible to be both a Christian and a cynic? I find my natural disposition to be rather cynical, though with the future hope offered by Christianity, and the fact that the Christian message is one of GOOD news, it doesn't seem to lend itself to a cynical worldview. But let's clarify what we mean by cynic.

cyn·ic (sĭn'ĭk)
n.
1. A person who believes all people are motivated by selfishness.
2. A person whose outlook is scornfully and often habitually negative.

If we are using the first definition then there is no apparent contradiction. Indeed, this definition congeals nicely with a Christian worldview. Selfishness is the sin underlying all sin, and as fallen, sinful humanity, it is inherent to our nature. Interesting to note that this point of view on the nature of man is more or less shared by most naturalists and atheists. One of the main driving forces behind evolution being self-interest and self-preservation (i.e. 'The Selfish Gene'). Anyhow, selfishness being a central motivator of people generally is not incompatible with a Christian worldview. Of course, if the definition is taken as an absolute i.e. all people are motivated by selfishness at all times and in every action they take, then that is, I think, incompatible with a Christian worldview, and this extremism gives way to the second definition.

The second definition is the one that is more difficult to reconcile with a Christian worldview. Negativity as a default disposition or outlook is not what I mean by cynicism. The sense of the word that I'm using is more the first definition, with a hint of the second. Though I think this might be the more commonly used sense of the word, and thus, the reason that the idea of being a Christian cynic seems to be an inherent contradiction, on it's face.

What I meant by cynicism, prior to looking at the definition, was: a default disposition of suspicion w/r/t people's motives in whatever actions they take or words that they say, not accepting things at face value, due to the selfish nature of humanity. Given this definition I think it's pretty reasonable to be a cynic, indeed, nearly imperative to be one, Christian or not.