In fact, part of the point of Jesus’ mission, to bring the life of heaven to birth on earth, was that from now on holy mountains wouldn’t matter that much. This wasn’t a new insight. When Solomon dedicated the Temple a thousand years before, he was quite clear that heaven itself wasn’t big enough for God, so that one single building couldn’t hope to contain him. Holy buildings, and holy mountains, are at best signposts to the real thing. If they become substitutes for it, you’re in trouble. That way lies idolatry, the worship of something that isn’t God as if it were.