My eye is also drawn to Woodrow Ave, the large, straight street leading directly to the circle from the ocean, which nobody has mentioned yet. This says 'ley line' to me. It's interesting that it only going one way.
Here's one idea: if I trace the path of that street northward, it appears to land in the San Franscisco Bay. What if something
EVIL was under the bay? Perhaps something recovering from wounds from an ancient fight with an archangel. And it *had* been feeding off of the energy of the ley line, but when this was discovered, the church/circle/Woodrow were built to stop the flow of energy and starve the beast out. But with nowhere to go, that energy is building to dangerous levels, and the church staff don't know what to do ... or perhaps are completely unaware of the growing problem.
Or perhaps the site is siphoning energy from the ley line to contain the creature, which fell below the site, rather than further north (as others have suggested).
I also noted that in the other direction, Woodrow appear to point directly at a small spur of land just south of the bay. Perhaps it was intended to direct energy
to something there, instead?
By the way, you might have use of this page I found:
http://www.santacruzpl.org/history/articles/29/, which talks about the history of the site, which dates back to 1890. Apparently it was named after the then-recently assassinated president James Garfield, who was also a preacher in the Disciples of Christ, who founded the church. I imagine that something could be made of that, too: perhaps Garfield was assassinated in an attempt to prevent him from accomplishing something major in the struggle between Light and Dark?
I think you have something really interesting to build on here. Enjoy!