I confess to being slightly shocked to read how you question, even condemn, a calling that God has ordained. Dr. Kent Brantly did not go to Africa because it served his purposes or out of what you so contemptuously call "Christian narcissism." He was called to this work by the One Who leads the church in its mission to the world. If he is like thousands of others that have done similar things, Dr. Brantly only went after much prayer and receiving sufficient confirmation.
In deploying His people, God does not, I can confirm, consult the latest strategic white paper from prominent right-wing think tanks or the blueprint for action from the Republican National Committee. He deploys His people according to His wisdom and for His purposes.
What we have here is a clear demonstration of God's wisdom versus worldly wisdom. Do you seriously suppose that Dr. Brantly would have contracted his illness if God had not ordained that it be so? It is true that many, myself included, do not see how this whole episode advances the cause of the Kingdom, but we are assured that it does. (Rom. 8:28)
Can Christians make mistakes, and can churches make mistakes? Absolutely, yes. We all have the tendency to follow our own way rather than God's way. Fortunately, popes and preachers notwithstanding, the plan for the salvation of the world is not in any individual's or church's hands, but in His alone. Do Christians have mixed motives? Of course they do, but salvation means that God will take care that those problems do no harm.
We need to get this straight:
(1) Christianity is not an ideology; it is identical to following the way of Christ.
(2) Christianity leads not to wealth, health, and happiness, but to the Cross.
(3) The Kingdom (the collection of all those who are following Jesus as King) does not need any worldly form of success to be and remain the Kingdom.
(4) The future of the Kingdom does not depend on
(a) convincing people to follow any particular moral code,
(b) persuading people to adopt certain views about culture, or
(c) raising up leaders to convey this or that message to the surrounding cultures.
(5) America is not essential (or even necessarily useful) to the future of the Kingdom.
Jesus' Kingdom is not of this world, but it is in this world. Through the power of the Spirit (and no other way) it will prevail. We who are called to missions serve at His pleasure, wherever and for as long as He pleases. It might often be important sometimes to think about the "how" and the "how much", etc., but the "what" and the "why" are totally in His hands. (See, for instance, Jonah.)
The reason that so many self-proclaimed Christians are confused about the role and destiny of Christianity is that they have derived a political philosophy and ideology from Christianity and follow that. Naturally, this different "way" is sometimes at variance to God's way, and this leads to questions that have no satisfactory answers within the domain of philosophy or politics.
The simplest answer is that the Christianity of political and social collective action is an idol. With all respect to those who have dedicated to fighting a particular social evil, I would rather have one person preaching about Christ than ten preaching about the evils of drink (or whatever the cause d'jour is), even if the latter is more "effective," because the people's true need is Christ. If, in order to get the necessary attention of people in need, the church must first meet some physical or mental needs, so be it.
By the way, I have nothing against good works and often seek to join in them. Also, I affirm that there is great benefit to exposing the world to God's wisdom. But these do not touch the world's fundamental need, though they may sometimes open doors. Furthermore, when these things are given to the world, they are expressions of the love of Christ, Who died that the world be saved.
One more point: Miss Coulter misuses Deut. 15:11. This command to Israel to care for the poor of their own land was like many other such commands, i.e., that Israel be distinct and an example to the surrounding nations. Israel was commanded to be separate from the other races and cultures so that it could serve as the light to the Gentiles and ultimately to harbor the Savior.
Christ erased all such borders. The church has as one of its charges concern for all the poor of the world. (Gal. 2:10) Like many another responsibility, the church does not seem quite equal to the task. Still, the Kingdom will ultimately overcome in this respect, too.
Christians in America need to drop the idol of political influence and start telling the world where true life, true freedom, true salvation come from.
Sounds foolish, doesn't it. All right, I will concede the point. Dr. Brantly is a fool. But I would rather be his kind of fool than yours.