Nobody has suggested that the earth does that (except during a lunar eclipse). One gets a half moon, for example, when the sun happens to be illuminating the moon from one side of it (as viewed from Earth).
Well, no because depending where an observer is stood upon the surface of a flat earth, the angle from there to the moon and the sun should automatically illuminate the surface of the moon making it appear full to the observer stood on earth! However, this does not occur because of the role of the 'dark sun' which has the affect of partially obscuring and fully obscuring the surface of the moon, which itself is flat like the earth! There are some that believe that the moon has two sides, for example, like a coin, with one permanently illuminated side, and the opposite side permanently dark like, for example, the 'dark sun'. In this module, the moon rotates on its own axis and the phases of the moon are created by the gradual turning of the illuminated part of the moons bright surface, which gradually decreases in size until the very last illuminated crescent exists on the right hand side! Then on the opposite side the crescent of the illuminated side of the moon begins to emerge, until it reaches full brightness in the form of the full moon! This explains the decreasing crescent on one side of the moon from full moon to new moon, whilst the growing illuminated crescent (the opposite part of the rotating two sided moon) commences growing from the opposite edge! Hence, how the waxing and waning phases of the moon come and go! The moon (negative influence) and the 'dark sun' on its reverse (positive influence) are for eternity bound together! The rotation of the moon / 'dark sun' affects the electromagnetic nature which exists inside the earth's firmament due to angles it makes to the sun (positive influence)...