In its simplest form, Agnostic means to have uncertainty about whether God exists.  It is not in itself a religion or religious belief.  It is more a concept.  It is the belief that there may or may not be an existence of a supreme being.  For the agnostic, there has been no evidence to support either theory conclusively.  In fact the lack of evidence has been the only real underlying principal that the agnostic has been able to "know".

This does not mean that a person who is of the Agnostic mindset does not have a moral code, or rituals.  In fact you can even see people who are agnostic who have created a belief system, complete with moral codes and rituals that seems like a religion.  Thus the concept can lead to confusion.

At the root of the Agnostic belief system is the belief that they just don't know if God exists or does not exist.  From this premise ways to operate have been developed over time.

There are those who operate from the perspective that they just don't know, and there is nothing else to it.  Then there are those who build upon it, they don't know, but have at least made a decision to operation with the assumption that he probably doesn't exist.  Conversely, there are those who don't know, but have decided it may be safer to operate from the assumption that he may exist.  You can even find some who will say that he does exist, but there is nothing known at this time about such existence, or that there will never be any possibility now, or in the future, that there could be anything to ever really know about God.

There are also those who were at one point Agnostics.  However, something changed for them, and they were able to satisfy themselves of the existence of God.

It is not uncommon to find people of the Agnostic persuasion who are researching, studying, and trying to get the question of existence answered.  They often will be much more willing to research the material, and not just accept it on faith or belief.  This can work for or against them. 

It works for them when they find something that finally answers the question for themselves, and they are able to move out of a "not knowing state" and into a more comfortable state of finally having some knowledge in this area.  There is always much peace for an individual when he gains knowledge in any area.

It works against them when they are simply finding that their research always results in more questions, and more answers that open up to more questions.  It can begin to feel like an unending nightmare.  It can become easier in fact, just to adopt the concept of agnostic and move on with their lives living by their moral code and codes of conduct.

A person who is agnostic is not necessarily immoral or unethical.  They can operate and live their lives as well as a person with strong spiritual beliefs in the areas of ethics and morals and codes of conduct.