THEORY: Lumon is a company that was established to...

Access and practice the occult through rigorous lab condition/scientific processes.

Since Season 1 I've had the theory that Keir Eagan, through the strange experiences in his life, accessed the occult.

However he didn't view it as mysticism or magic, but instead as a not yet honed or understood system of natural laws. His epiphany came when trying to control it via the Four Tempermants which is similar to the Theory of the Four Humours, which would have been the prevailing medical paradigm at the time he was introduced to medicine during the American Civil War, just prior to the widespread adoption of Germ Theory.

Rather than approaching the occult with esoteric symbolism, dripping candles, pentagrams and suchlike, Lumon is working on methods to hone and specifically target it via an unconventional but strictly professional way of working. Lumon and the Eagans do not necessarily know what the occult is or where it comes from, but have figured out that performing [×] action at [y] time will consistently produce certain results.

As such the various departments at Lumon are performing occult practices but in a managed setting. Macrodata Refinement is performing numerology/Kabbahlism. Optics and Design are producing 'empty vessel' props to be used in voodoo, in the same way a voodoo doll is an empty vessel representation of a real entity in the real world.

The goats are raised for the performance of ritualistic sacrifices, hence why the baby goats were 'not ready', and in the trailer we see goats being shepherded around an indoor pasture by someone dressed as some eldritch creature.

The reason Lumon must sever its employees is because the occult requires 'empty vessels' to work through, like the props made by O&D. Outties have too much mental baggage to allow the process to function properly, and given the general impression of occult practices in the outside world would cause them to become defiant, which would affect the efficacy of the rituals.

Like I said, Lumon doesn't think of the occult as like an Eyes Wide Shut party or anything like that, although elements of such beliefs have began permeating into the company (like the infamous Waffle Parties), but instead see it as a previously unharnesed and undiscovered force that can be tamed and directed through rigorous scientific understanding.

That's my theory anyway. I'd be interested to hear what you all think about it.