Fire is a chemical process of combustion, releasing heat, light, and various reaction. At a certain point in the combustion reaction, called the ignition point, flames are produced. The flame is the visible portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different.

Its the same way with the Holy Fire of God it removes impurities, refines us, designs us and establishes us into a unstoppable soldier of God!