At the end of a social event on the weekend before Mardi Gras, a casual friend asked a surprising question. I was bedecked with beads, primarily in purple and gold. This Catholic friend comes up and says something like, "Why are you all dressed up for the Christian holiday? Don't you believe that anyone who believes in God is stupid?"
Dumbfounded. It took me a moment to parse this and compose a reply. As we were all heading out the door, I didn't have time to fully answer all the implied misconceptions. So I said something on the order of, "I don't think that; I know many smart people who are faithful."
Let me first detail a minor misconception. Sociologically, rituals are important. Mardi Gras (literally Fat Tuesday, also Shrove Tuesday) was adopted by Christians from the earlier Carnival, and Saturnalia before that. It is a long standing late winter festival ending the season of harvest plenty in the days when food preservation was limited, and entering the lean period of rationing until the spring produce appeared (greens, lambs, milk, etc). And festivities are fun, whatever the nominal purpose. The Holy Roman church had so successfully rebranded all the pagan festivals that most Christians are unaware of the deeper not-Jesus purpose behind them, even as they embrace all the pre-Christian trappings.
But the big issue is the perception that I, an an atheist, think that Christians (the majority faith at present time and place) are stupid. Many converted Atheists do vehemently decry their former faith and deride its practitioners, as do Dawkins and Hitchens. My parents converted from religious to irreligious, and so I was raised without a particular god and with their lower expectations of people of faith. But that didn't stick.
I grew up as a closeted atheist. On Sunday mornings I was dragged to a secular Sunday School where I had to wear jacket and tie from the age of 5. It didn't fool my church going peers. I opted for the less hated liberal-Jew label that try to explain that all invisible friends seemed equally improbable to me. I endured various epithets in public schools hurled at non-Christians by the God fearing. But as I grew older and my peers become more reasonable, I started talking to them about such things.
I was actually less surprised to find people of deep faith at my fairly-high-standards college than I was to find sports fans. One of my closest college friends was a Young Earth, Born Again sort. I admit that I would sometimes light his fuse in a room full of geology or astronomy types, just to see to what heights his rationalizations could wax. (Anyone else visualizing Ceiling wax?)
I have also been reading arguments from both sides of the God conjecture since puberty. The problem is not whether one side is smarter, but which is the set of assumptions on which their sense of reality rests. Either cause and effect are real and the universe is knowable through a continuing and contentious process of observation, documentation, and modeling (science), or else the continually meddling god of Christianity is possible, as was declared by ancient authority. The majority of the American founders were Deists who believed that if there was a creator God, he did not meddle in the day-to-day affairs of men. I can accept that God, but still don't believe in it. Cosmologists and astronomers are pushing his creative acts farther and farther to the margins.
So although I acknowledge the high correlation between less-learned people and deep faith, I do not assume that having faith implies that people are stupid.