I'm considering the God of the Bible because the miracles I've heard of are specifically Christian, and therefore either they're valid (and therefore Christianity is true) or they're invalid

That's not true. Various beliefs systems do allow for intentions to manifest paranormal effects. You can also explain quite a lot with karma.

If you search a bit you will also find that Christianity isn't the only religion or belief system that makes miracle claims. Especially when it comes to straight bible Christianity. Quite a lot of New Age folks for example believe in reincarnation with is not compatible with the standard idea that the bible proposes.