The metaphor used by the atheist is a simplified way to explain why celestial bodies like the Moon do not collide with each other due to their orbital motion. While it can help visualize the concept, it's important to note that it is not meant to be taken literally.
In reality, there is no physical "string" connecting the Earth and the Moon. The Moon orbits the Earth due to the gravitational attraction between the two bodies. This gravitational force keeps the Moon in a stable orbit around the Earth, much like any satellite in orbit around a larger object.
The gravitational force between the Earth and the Moon is a result of their masses and the distance between them. It is this force that allows the Moon to continuously orbit the Earth without colliding with it.
So, while the metaphor of a "string" can help convey the idea of objects in orbit, it is not an accurate representation of the actual physical mechanism involved. The gravitational force, rather than a physical connection, is what holds celestial bodies in their orbits.