But here we go.
The Doctor-Companion relationship as a metaphor for our trust in God
There is a lot of discussion among Christians about what it means to trust God, and how He proves himself faithful or trustworthy. Many people turn their backs on Him, for a short while or forever, because they feel that they trusted and were betrayed, trusted and were let down. They asked for health and happiness, for a particular job or child or home, and didn't get them. They asked for protection, but were hurt anyway. They asked for answers, and found His voice silent.
Partly because of this, I've heard (and used myself) a couple of related metaphors used to describe life in this world. It's not a place we belong, it's not an easy place to live. It's not home. Life is a battlefield, the setting for a war in which we are spiritual soldiers. It's enemy territory, in which we are ambassadors, or spies. A duty and a journey, where we serve.
And that fits well enough, but it doesn't really answer the question of trust. The facts of God seemingly not coming through place all the effort on Him. The metaphor of war, of being soldiers in service, places a lot of the effort on us. "Faith is being sure of what we hope for, and certain of what we do not see."
But it seems to me that faith need not be completely blind, and life need not be hopeless. That's why the relationship of the Doctor and his companions struck me so strongly. The type of trust going on between them (newbie fan: between the ones I've watched, anyway) is a peculiar sort of trust. It's a choice, one which has to be actively renewed in the face of danger and doubt; and it's not always based on actions, but on the Doctor's character.
Traveling with the Doctor is exciting, adventerous, amazing. (Fantastic?) It's not for the faint of heart. It's entirely possible to land in the middle of a war zone, of a battle between robots races or savages, of a diplomatic disaster or the outbreak of an epidemic. In fact, that's where the Doctor thrives, and to travel with him a companion must learn to do the same.
Admittedly, the Doctor presents a good risk for trust: he's brilliant, clever, knowledgable, empathetic, enthusiastic, moral, and even loving, after his fashion (which may not be quite like ours). Most importantly, he does not leave people behind. If a companion is captured, she knows that the Doctor will come for her; if a companion is in danger, he can call for the Doctor, and if the Doctor can come, he will. He's dependable.
That, to me, is a much better image of the Christian life. We're on an adventure. This world isn't safe, it isn't secure, but we're travelling with Christ. Even if we're captured, tortured, hurt or ill or left behind, He'll come for us, heal us, rescue us. We can trust Him.
In "Parting of the Ways," the Dalek Emporer taunts Jack Harkness about the Doctor's willingness to destroy all life on Earth in order to wipe out the Dalek race. How can Jack trust such a man, who seems willing to sacrifice him to meet a goal?
Jack's response is perfect, and perfectly sincere: "Never doubted him, never will." He knows perfectly well that the Doctor may have to use the Delta wave, but he trusts the Doctor even in the extremity of that situation. That's faith, if you like. Knowing and still trusting.
Let us go forth in such faith, and take the adventure that comes to us.