Awesome satirist, not so great a theologian.
When people talk about faith, they are usually referring to the Christian faith and for militant skeptics, their point in deriding faith is that belief in the cardinal points of orthodox Christianity is no different from believing fairies cavort in one’s rose garden on a daily basis. Most people would agree with Twain’s definition of faith and equate it as the same as any irrational and nonsensical belief.
The author of the New Testament epistle to the Hebrews defines faith as, “the assurance of things hoped for, the conviction of things not seen.” Now at first glance this appears to support Twain’s supposition, but let’s take a closer look.
The Greek word behind "faith" in the NT is pistis. As a noun, pistis is a word used as a technical rhetorical term for forensic proof. As a legal term, it is a verdict based on testimony and evidence.
The phrase “blind faith” is then a true oxymoron, two contradictory words that have no business being together.
The Christian pistis is based on the verdict that there was an itinerant, historical rabbi in 1st century Palestine who made claims consistent with Messianic prophecies that had been recorded over several millennia. This man also made claims to have a special relationship with the Jewish God, Yahweh. Because of the political climate of the time, this man was publicly executed, but his followers not only made the outlandish claim that he physically rose from the dead, they were willing to die for that supposition and many of his followers did just that, sometimes under torture.
As one looks at the possibilities of what this man, Jesus of Nazareth, could have been, there are four main options. He was a liar, a lunatic, a legend, or he was exactly what he claimed to be which was the Son of God and the Jewish Messiah who had come to provide salvation not only for the Jewish people, but also for the entire world.
And so, people make up their minds about Jesus and what he represents, if they are honest with themselves, by looking at the evidence. They are judge, jury, and executioner and must make up their own minds about him, but the verdict that I have come to, that Jesus is exactly who he said he was, is not based on blind faith, but a careful weighing of the evidence from my understanding of archeology and history, my knowledge of how to read historical literature, the historical impact of Christianity, and a careful study of the person of Christ himself including the culture and times in which he lived. As there are an estimated 2.2 billion Christians in the world who have come to the same conclusion as myself, to think that so many people simply adhere to “blind faith” without any logical reason is more akin to Mark Twain’s definition than true faith itself.