At the bottom of page 16:
As your tribe grows, new God Powers will be unlocked.
And at the top of page 17:
As your believers establish themselves here in the center of Isola, they may start to construct a statue in your honor. This statue will augment your Divine Energy. In addition it will house relics that will increase your maximum Divine Energy.
Under the God Powers heading:
The more energy you have, the more God Powers you will have access to.