And then the conversation moved to be specifically about evangelicals.
But getting back to the original point, I don't really agree with that. There are dozens of presidential candidates who failed to connect with average voters. They're called the losers. You see at least one every four years.
As for him being "secular", I'm not sure what that means in this context. He was running for a secular office. He wasn't running for Pope, so in that context, both he and Bush were secular.
Do you mean that he didn't wear his religion out on his sleeve? Well, Jefferson didn't either and that didn't seem to hurt his presidential aspirations. The idea that a president has to put on a religious display in order to "connect" with average (religious) voter is a relatively recent phenomenom in American politics. Kennedy's problem in 1960 was that some people thought he wasn't secular enough. He had to reassure (ironically, mostly the evangelicals) many that he was going to respect the separation of church and state and not take orders from the Pope about American policy.
Yes, presidential speeches often contained some generic platitudes about faith and God, but the idea that the American voter needed to think that the candidate attends a church that's just like theirs is relatively new concept. And one that most of the founding fathers would have found repellent.
Getting back to Dukakis, he had said he was Greek Orthodox. Whether his devotion to that church was sincere or even fervent enough to satisfy some people is a question I find very strange.
Being a regular church going is hardly an indication of being honest or trustworthy. Just look at George W. Bush.