Atheism is a belief. Agnosticism is a philosophy. An agnostics accepts the own recognition (in sense of the German word "Erkenntnis") not to be able to know whether god exists or not exists.
Agnosticism is no belief at all but the philosophical insight [still] not to be able to solve the problem whether god exists or not exists (or both). What to do with this knowledge or how to interpret this is a totally other thing. I am for example an agnostics who believes in god. Very most Christians who believe in god are agnostics - whether they call this so or not. But on a mysterious reason today the word "agnosticism" is often used instead of the word "atheism".
Atheism is nothing else than a belief. It's "only" the spiritual belief not to believe in spirituality. And like all other forms of religions atheism also has to live with contradictions, paradoxes, absurde sects and murderous attitudes. Also atheists are human beings. Atheism is no way to switch into a position where recognition is independent from humanity - in all good and bad forms of humanity.
Also atheistic scientists for example have to believe in a common truth between all sciences - otherwise to do science makes not any sense. Science believes in one common truth and not in many truthes depending on different perceptions and positions. To believe in one common truth which connects all people with each other is a form of belief in god.
One of the worst mistakes today is to think human beings are god on their own ("supermen" in sense of Nietzsche) and manipulations of the human languages bear a "new" truth. Nothing bears a new truth. Truth was always what it is. We do not make it. We recognize - if we are lucky - what's wrong. And as long as something is "definetelly" not wrong it's true. But this "definition" is not man made. It's universe-made for scientists. And Christians believe in very most cases the universe is made from god - out of nothing. This belief is not essential for Christians - we just simple found not a better "solution" or plausibility in the last 1600-1700 years. But somehow this belief seems to frustrate a lot of not-Christians.