In the past, I've described myself as a "principled optimist". Likewise, I made a comment a while back on Facebook that pessimism is the result of bad theology. All that needs a little clarification and I'm just now getting around to defining my terms.
1. A principled Christian optimist is not surprised when hardship comes. In fact, he expects it as the natural consequence of living in sin-cursed world. His optimism is not based on circumstances but perspective.
2. However, the perspective of a principled optimist is not a subjective, relativistic mind-binding. It's not so much about looking on the bright side as it is looking at reality - that is true Reality, the Person of God. A Christian optimist sounds more like Paul than Pollyanna.
3. The Christian optimist rests in the character of God as his source his optimism. He places himself in the stream of Christian thought that adheres, at least on some level, to the theory of Gottfried Leibniz which states the world that exists is the best of all possible worlds. He also agrees with G.K. Chesterton that the real world is far more magical than any fairy tale.
4. Leibnizian theory: Because God is omniscient (all knowing) He knew all possible worlds and events that He could have brought into being. Because He is omnipotent and sovereign (all powerful) He was perfectly capable of bringing any of those worlds and events into being. But because He is omni-benevolent (all good) He chose to bring into existence the best possible world and events. This is the Christian's basis for optimism.
5. However, the principled optimist also recognizes that God's original world has been corrupted by humanity's fall. But he also recognizes that even the most horrible events ultimately conspire toward the glory of God and the good of humanity. Take for example the most horrific event in human history - the crucifixion of our Lord. It is also in another sense the best event in human history for it brought God glory and humanity redemption.
6. The principled optimists trusts God to work all things together for good, believing that even the most horrid of trials will be used by God to accomplish His ends. Therefore, the Christian can be optimistic even as he faces tribulation.
7. The principled optimist reads Romans 8 a lot.