To show that they are poor
The first is to describe why something HAD TO happen. The second is to describe why something DID happen. Just "the reason" is what it is, and it can be used in three different ways. You used two of them in your question
Virus lack metabolic pathways or any other life activity. This is the reason virus is known as particles and not as life form. they require their host for the replication and dependent of host machinery.
Reason Kufonya has written: 'Pfupajena'
mental capacity, intellect
ReligionReligion.
Describe the Aztec gods
An author's purpose, normally in their written expression, is the reason for which they compose the text. The author, therefore, will already know his or her purpose, and so has no reason to determine it.
42 of course..
Dave Reason has written: 'A version of the theory of regression'
Slang is the only reason that urban dictionary exists.
basically 50 cent said no.
"Illogical" is an adjective. It is used to describe something that is not based on reason or logic.