The earth's core.

Just stop. You're making us all look bad.

But not worse 

As a gay, white christian male, I have been told I'm going to hell for almost three decades. They say volcanoes spew out some some of hell fire from the, "center of the earth". Do the fires from hell perpetually burn, thus making volcanoes erupt? I mean, I don't think the earth has a hot core, with the mantle and the crust on top. So hell must be underneath us and very, very real?

If this is a genuine question, don't bother wasting your life by taking on board what other people think about you; well done for being open and honest about it. Without love there would be no nature at all, so viewing pretty much everything to do with love (in all it's shapes and forms) as a "sin" is obviously pretty broken. As for your actual question I'm not sure who it's directed at but "down there" works better with a sphere, and looking at the science is the best place to start. Instantly assuming that hell is "very, very" real is of course a little naive - nobodies seen it, so that makes it less likely; the scientific explanations have side effects which can be easily seen and predicted on the surface, such as how earthquakes work and continental drift. They match up with what we observe, so that makes them more likely. A main observation is also the existence of the Earth's magnetic field which wobbles in strength, suggesting that there's something metallic and it's also liquid. Liquid metal => it's probably pretty hot!