The effect is caused by the galaxies' gravitational field, which draws energy from the light emitted in the center of the cluster, thereby shifting it further into the red region of the spectrum. Light emitted from the peripheral areas of the cluster, however, is shifted to a lesser extent. This is because the light rays emitted from the near side of the cluster remain within the gravitational field for a shorter period of time and therefore are less affected. In contrast to this, light emitted from the far side of the cluster receives additional energy on its way to the center, of which it disposes only on its subsequent route out of the cluster. This is why the wavelength spectrum of the whole galaxy cluster expands.
The finger of God is a natural effect and does not, unfortunately, amount to a ►proof of the existence of God; in fact, it does not even prove that God has any fingers in the first place.