You ever watch shows like "Lie to Me" and "Bull", the new one with Michael Weatherly? While every case has variables, the basic truths tend to hold for human behavior, making analysis and prediction possible. It's no different than the FBI's profiling experts.
Hard sciences are like chemistry and physics, where the formulas will most times give consistent and predictable results.
Soft sciences require expertise in the basics and experience so the case can be properly analyzed.
"Hard science and soft science are colloquial terms used to compare scientific fields on the basis of perceived methodological rigor, exactitude, and objectivity.
Roughly speaking, the natural sciences are considered "hard", whereas the social sciences are usually described as "soft"."
Science requires a a methodology, repeatable results and applications in the real world. I realize you're stating pure opinion with the "98% religion" comment, but there's no set ratio like that. Each case will be slightly different given the variances in factors impacting the behavior.
Let's face it. If human behavior wasn't predictable and easily manipulated, Las Vegas would have gone bust long ago! 
I am in a profession that is ruled by physics. It's that hard science aspect that I enjoy. I can prove to you that I am right by the LAWS of physics. Yeah, there are architects who still believe in antigravity or that a beam that is designed to span 20 feet can somehow be manipulated to span 40 feet based on beliefs. Well, if you believe so, set up the beam and stand under it when you load it. That will prove to you that it doesn't work. . .

Sometimes lessons are best learned the hard way.
I've also learned through courses in leadership and management that the brain takes in and processes information differently. Meyers-Briggs and others really show that dynamic. When I was in a leadership development program, there were two other engineers in my group with two marine biologists. They marine biologists were very nice people, but it just seemed like they somehow just weren't getting what I was talking about with the engineers and vice-versa, even where at times it seems like we were in complete agreement on an issue. When we were in a course where we had to take the Meyers-Briggs test, it wasn't really a surprises that the marine biologists were on the opposite ends of the spectrum on all except for the intro/extravert. There are examples of how each "side" would go about solving a problem of approaching an issue and each group had to list things on a board. When the groups revealed to each other the other's points, it was like we were talking to aliens. It really hit home on how differently people can view various topics.
One example of how differently people thing, especially in extremes was in the part of thinking vs feeling. A female marine biologist was extreme to the feeling side (I know, shocking right). Anyways, the discussion was about how the main point of the exercise is to realize how the thinkers and feelers approach things differently. That the important thing is to realize that one is not better than the other, just different and that is important to respect the other view points. She seemed to nod her head in agreement, but sort of had this look like something was stewing in there. When asked later, she was still super frustrated why people didn't seem to understand her view and how she felt the feeling view point was better. Total facepalm from the group, even those who leaned toward feeling.
In school, I did well in biology, but it just didn't click like things did with physics and chemistry. Hence I didn't pursue a career in the fields of biology and other soft science. Anyways, just thinking that we have people here who like to argue extremes. While I generally give people the benefit of the doubt and try to see their view points, but when they are so set that they can't see the forest beyond the trees. . . maybe one day they will hit one of the trees.