I removed the beginning of an anti-Creationist argument. "Viruses were created by God".
The rest of this pro-evolution, atheistic argument goes like this: Although there is enormous beauty to be found in the plants and animals of this world, as well as in the physical planet itself, there is also much ugliness. Beauty and ugliness are, of course, human perceptions, but then so is the belief that an intelligent Creator is necessary to explain the existence and nature of the world. Innumerable examples could be cited of rather nasty biological realities which are perfectly understandable in terms of evolution, but which make no sense whatever in terms of design by an infinitely intelligent, wise, and compassionate Creator. Every living creature, including plants, must contend with the ravages of diseases and parasites. Most disease-causing bacteria and viruses, which exist in encyclopedic profusion, serve no useful “purpose” whatever except to infect other creatures and to make their lives more difficult or shorter.’ 
Added a few more specifics and details to how viruses reproduce. Amazing little things, existing only to their genes into the future.--Snotbowst 23:15, 16 May 2008 (EDT)
I've added some information on classification and am working on rewriting the parts about replication. There were some parts in the old article that were confusing or incorrect, so I tried to make them a little more simple.Seanpk 19:57, 20 April 2011 (EDT)