The Heavenly Stone of Taiyi contained a large amount of energy, which was more powerful than Celestial Core Power. It was similar to Heaven's power and was, in fact, the Gods' Strength.
Xu Que had found all this out because the System had informed him of it. It had also informed him that the Heavenly Book of Taiyi that was in his possession came from the Heavenly Stone of Taiyi. It was just a part of it that had broken off.
Therefore, Xu Que was quite certain that this so-called Chosen by Heaven Ceremony was actually a ceremony that was being used to select a person whose Mind Sense could communicate with the Heavenly Stone of Taiyi and be given another Heavenly Book of Taiyi by the Stone.
Such a person would be called the One Chosen by Heaven.