Whereas your greater faith in his inability to lie allows you to uncritically accept everything he says.
Here's the way I see it. (I'm glad you asked.)
On those rare occasions when this subject comes up around people with no, or not much, scientific education, I see two types of responses. From non religious people, I see people say, "That creationist stuff is a bunch or religious yahoos trying to put their religion on us." From religious people, I see people say, "I don't know much about science, but if God didn't want it to happen, it wouldn't happen."
The ID/Creationist/God is necessary crowd goes slightly farther than that. They say, "There's no way it could have just happened. There had to be a God pushing things along." Among those people who are inclined that way and have no scientific education, they can believe anything they want. Young Earth creationism? Why not? They don't know any better.
Behe, and those like him who haven't written as many books, have it a bit harder. Behe is a scientist. He knows that the evidence says the Earth is old. He can't look at the data and be a YEC. He knows about DNA, which also means he knows how similar DNA of different species are. He knows that's true even about the DNA that doesn't appear to do anything, and he knows that the best explanation for this is that the DNA came from a common ancestor.
On the other hand, he doesn't know a few things. He doesn't know how the first DNA came together. He doesn't know how the first cell components came together. He doesn't know the sequence of events that would transform one species into another. He doesn't know any of these things because no one knows any of these things.
And so, he says God did it. He sees geological, astronomical, and other evidence that says the Earth is very old. He sees biological evidence that says diverse life came from common ancestors. He sees that DNA could alter from one species into another, but he can't see the sequence of steps, and he figures that if he knew the sequence of steps, it would be very complicated, and he concludes that, in fact, it would be too complicated to happen by accident.
And that's his (pseudo) theory. It's classic "God of the gaps". It's classic "argument from ignorance". However, let's not fool ourselves. There are gaps, and we are ignorant. There really are things, important things, about the development of life that we can't explain, yet. Behe, and countless laymen, think they've found an explanation. God Did It.
There's really no need to assume that he's lying. He's just hiding in the gaps. Fallacious? Certainly. But lies? I don't see any need to believe that, and I don't think it adds anything.
And that's also how scientists can be creationists or many variations thereof. There are still lots of gaps where God can fit it. It's hard for a geologist or astronomer to be a YEC, but we know so little about the process that there are very few other areas of scientific exploration where creationist (etc) ideas are flatly contradicted by real, scientific, data.