When one considers why God of the ancients was visualized as a fiery aspect, they are brought to observe the nature of combustion:

Fire is about transmutation:

The simple action of lighting a match is basically, rubbing the surface to induce static electricity, which further along, excites the molecules of the match's head into a higher energy state which allows them to disconnect from the rest of the carbon/wood and be unified with molecules of oxygen. The warmth from the initial reaction drives the rest of the head to light up due to temperature increase in the area.

The unification of carbon with oxygen gives us Carbon Dioxide, but the process itself in which the elements combine is recognized by us, as fire. 

Fire releases light and changes temperature from the aforementioned reaction, but most importantly, it displaces energy lying from the carbon bonds into the air, leaving behind it whatever couldn't shift, the low entropy state exhibited by ashes. 

This allows us to picture ancient gods as beings of fire, due to their capacity to unify two seemingly separate entities.

Zeus or Dias means 'to pair' and 'to divide'. Zeus' thunder, due to its capacity to create fire, causes separation within units of carbon in order to induce unification with oxygen. This has metaphorical implications when one considers metaphysics.

 Matter exhibits a unique form of bipolarism with an end goal being a return to motionlessness. There are two ways to achieve this end-goal: highest entropy or lowest entropy. 

Now that we figured out what FIRE stands for and why it is divine, let us seek the rest of the elements....