Most people believe in evolution so that their friends will like them
Near the end of the piece, Martens says "But many of these very smart people cling to evolution because they want the approval of their peers." Mehta mocks this line, saying "We accept evolution because we just want people to like us. That’s really the secret of the whole scientific method right there." Nevertheless, I think Martens is right about most people who say they believe in evolution -- as well as most people who say they're creationists.
The level of understanding of the theory of evolution in the general public is extremely low. Even among people who are the most strongly convinced that evolution is the correct explanation for the origins of life, misinformation abounds about biological processes, fossil evidence, and other important aspects of evolution. Because people have limited mental space, and because an understanding of the details of evolutionary theory has little practical usefulness to the average person, most people don't retain a solid base of knowledge about evolution. On the other hand, one's position on the basic question of "evolution or creationism?" is quite important. It's a way of signalling what kind of a person you are and what kind of society you want to live in. I'm pretty sure I would have a big negative impact on a lot of my friendships if I posted to Facebook that I had carefully considered the issue and come to the conclusion that creationism was true. If you sign up for an OKCupid account, one of the first match questions they ask is about evolution vs creationism, because it's such an informative question in sorting out which of these thousands of potential dates you're likely to be compatible with.
Thus, for most people on either side of the debate, their position on evolution vs creationism is largely a product of aligning themselves with a cultural group. That doesn't mean people are being completely irrational or arbitrary. Certainly aligning yourself with the group that contains the actual experts who have followed a rigorous method for determining facts about the world is not a bad approach if you don't have the time to go through said rigorous method yourself. But it does mean that social factors play at least as big a role in whether the average person accepts evolution as logic and evidence do.