What is so delightful about all these questions is that all of us have beliefs, but none of us really know.
Belief, in general, precedes rationalization. But rationalization almost invariably supports the initial belief. Sure, our ideas change, and we like to think it's because we've carefully researched things and the facts have changed our minds, but this is a delusion. What happened was that the zeitgeist surrounding us changed. Either our social/family circle changed, or the set of things our family and friends actually believe has evolved and changed. Change in "what everyone knows" does occur, but it in general does not occur within a single person, as an event within that person.
It is a gestalt that emerges from the community. Well-positioned media can, with a delicate touch, introduce gradual change. From The Atlantic to Fox and Friends, media manipulates our ideas, and we think we're being rational.
Even an apparently simple question like "Is the carbon footprint of Wind Power positive, negative, or neutral?" is fractally complex in several dimensions, and admits nothing even slightly resembling a factual answer. Further, it isn't even a relevant question. The relevant question would be "If we reconfigured our society around wind and solar power, could such a society simultaneously resemble our current one, while being carbon-footprint-negative?" which is a vastly more complex and unknowable question than the first one.
Basically, we believe the things we believe because they fit in with the world view we hold because of stuff our Dad told us.
I certainly believe the things I believe, but I am not so foolish as to imagine they're factual. I think my after-the-fact rationalizations are pretty solid, but there's no denying that I almost never rationalize away a previously held belief. Either my Dad was eerily right about everything, or I've probably got some stuff wrong. I just don't know which stuff.