Our micro enemies, on the other hand, are micro-organisms, which are not a part of our bodies, yet which have somehow penetrated our bodies, eventually stimulating the defence army therein.

Every foreign cell that enters the body is not, however treated as an enemy. Foreign matter constantly enters our bodies as we eat, drink water, or take medicine. Yet our body does not initiate a war with it. In order for the defence cells to perceive a foreign substance as an enemy, certain conditions are taken into consideration such as the size of the molecule, its rate of elimination from the body, and its way of entering the body. 
 
Bacteria 

Among our innumerable micro enemies, bacteria have an established reputation. 

Bacteria, which enter the human body in multiple ways, instigate a fierce war in the body. Sometimes ending up with quite serious illnesses, these wars explicitly reveal the power and ability hidden in an organism the size of a few microns (a micron is one thousandth of a millimeter). Recent research has shown that bacteria have an extraordinary resistance even to the most severe and harsh conditions. Particularly, the bacteria known as spores are resistant to extremely high temperatures and drought for extended periods. This is why it is difficult to destroy certain microbes. 
 
Viruses

The human body resembles a very valuable diamond stored in a safe, receiving the most intensive care and protection. Some of the organisms that try to invade the body act like experienced thieves. One of the best known and most important of these thieves is the virus. 

This organism, whose existence we became aware of with the invention of the electron microscope, is too simple-structured and small to be considered even as a cell. Viruses, which vary in sizes ranging from 0.1 to 0.280 microns, are excluded from the world of living things for this reason.2

Although categorized as being apart from the world of living beings, viruses indisputably possess at least as exceptional abilities as all other living beings do. A closer examination of the lives of viruses will make this fact more apparent. Viruses are the compulsory parasites of living beings. This means, they cannot survive if they do not settle into a plant, animal, or human cell, and consume its food and energy. Viruses do not have a system that would enable them to survive on their own. As if they are aware of this, they deftly slip into a cell, and after invading the cell, with the same deftness turn the cell into a "virus production factory" that produces its own copies. 

This plan developed by the virus to invade the cell is extremely sophisticated and intelligent. In the first place, the virus must determine whether the cell is appropriate for itself or not. It has to be very careful and meticulous in this decision, for the smallest mistake may cause its death. To avoid such an end, it uses its special receptors to check whether the cell is appropriate for it or not. The next important thing it does is to carefully locate itself within the cell.
The virus confuses the cell with the tactics it employs and avoids observation. 

This is how the events develop: the cell transports the new DNA of the virus into its nucleus. Thinking that it produces protein, the cell starts to replicate this new DNA. The DNA of the virus hides itself so furtively that the cell involuntarily becomes the production factory of its own enemy and produces the very viruses that will eventually destroy it. It is indeed very difficult for the cell to identify the hereditary make-up of the virus as that of an invader. 

The virus locates itself within the cell so well that it almost becomes a part of it. After the multiplication process is over, the virus and other new viruses depart from the cell to repeat the same process in other cells. During the process, depending on the type of the virus and the cell, the virus can kill the host cell, cause harm to it, modify it, or simply do nothing. 

The question of how the cell, which operates under a very strictly monitored control mechanism, can be deceived into becoming a virus factory is still unanswered. It is quite intriguing that viruses, which have a highly specialized structure, but which are not even classified as living beings, could act so intelligently, think up, and plan such effective strategies. The secret of this phenomenon lies in the existence of a Creator, Who created these organisms with the abilities they possess. 

The features of the virus are perfectly designed to enable it to make use of the system operating in the cell. It is obvious that the power that created the virus is also well informed about the extremely complex working principles of the cell. This power belongs to God, Who created the virus and the cell into which it will settle, as He created the entire universe. 

The virus, which, with its miniscule structure, can inflict and sometimes even cause the death of the human body, which is millions of times bigger than itself in size, is a being specially created by God to remind people of their weaknesses.

2- George Gamow, One Two Three... Infinity, Bantam Books, 1971, p. 245