Suppose you're a protestant, and you want to convince other people to do what the Bible says to do. Would you persuade them by showing them that the Bible says that they should?
Now suppose you're a rationalist, and you want to convince other people to be rational. Would you persuade them with a rational argument?
If not, how?
ADDED: I'm not talking about persuading others who already accept reason as final arbiter to adopt Bayesian principles, or anything like that. I mean persuading Joe on the street who does whatever feels good, and feels pretty good about that. Or a doctor of philosophy who believes that truth is relative and reason is a social construct. Or a Christian who believes that the Bible is God's Word, and things that contradict the Bible must be false.
Christians don't place a whole set of the population off-limits and say, "These people are unreachable; their paradigms are too different." They go after everyone. There is no class of people whom they are unsuccessful with.
Saying that we have to play by a set of self-imposed rules in the competition for the minds of humanity, while our competitors don't, means we will lose. And isn't rationality about winning?
ADDED: People are missing the point that the situation is symmetrical for religious evangelists. For them to step outside of their worldview, and use reason to gain converts, is as epistemically dangerous for them, as it is for us to gain converts using something other than reason. Contemporary Christians consider themselves on good terms with reason; but if you look back in history, you'll find that many of the famous and influential Christian theologians (starting with Paul) made explicit warnings against the temptation of reason. The proceedings from Galileo's trial contain some choice bits on the relation between reason and faith.
Using all sorts of persuasive techniques that are not grounded in religious truth, and hence are epistemically repulsive to them and corrosive to their belief system, has proven a winning strategy for all religions. It's a compromise; but these compromises did not weaken those religions. They made them stronger.
This comment is in reply to some ideas in the comments below.
In my opinion, my rationality is as faith-based as is a religious person's religious belief.
Among my highest values is "being right" in the sense of being able to instrumentally effect or predict the world. I want to be able to communicate across long distances, to turn combustible fuel into safe transportation, to correctly predict what an interstellar probe will find and to be able to build an interstellar probe that will work. Looking at the world, I see much more success in endeavors like these from science and rationality than from religiosity or appeals to god. And so I adopt rationality as it supports my values.
I also want to raise healthy, happy, "good" children. My one child who dabbles in alcohol, drugs, and petty theft, I am pretty sure I could "help" him by going to church with him. I've known many people who are effective at doing things I see as good because, it seems, of their religious beliefs and participation in churches and religious communities. I liked being a Lutheran for a few years. One night I told our pastor that I just didn't believe in god. He told me he thought half the church had that happening. Even so I couldn't stay engaged.
I feel the loss of religious faith as a sorrow, or a pain, or a burr under my saddle, or something. But I can't justify it, or more importantly, I can only pretend to believe, actual belief does not seem to me to be a real option anymore.
And it turns out I have enough "faith" in scientific rationalism that I won't even pretend I believe in god. I choose to believe that staying consistent with rational principles will payoff more for me and those I care about than will falling back to the more accessible morality of religious faith. It is a leap of faith, especially in light of "rationalists win." If my son were to become an heroin addict and devote his life to petty theft, jail, and shooting up, AND I could have prevented that by bringing him to church, I will have paid a price for my faith, as much as any Christian Martyr who was harmed or whos family was harmed because he did not deny his Christian belief.
People who think their rationality does not come from a faith they possess remind me of religious people who think their belief in god is just right, that it does not come from a faith that they possess or have chosen.
Taboo "faith", what do you mean specifically by that term?