If atheism is a philosophical view then it is either the rejection of theism due to it's arguments as not convincing or a positive argument based on naturalism. Every atheist argument is based on rejection, naturalism or a mix of both as both a rejection and proposed alternative.
To quote Ernest Nagel (American philosopher early to mid 20th century)
"I shall understand by 'atheism' a critique and a denial of the major claims of all varieties of theism... atheism is not to be identified with sheer unbelief... Thus, a child who has received no religious instruction and has never heard about God, is not an atheist - for he is not denying any theistic claims. Similarly in the case of an adult who, if he has withdrawn from the faith of his father without reflection or because of frank indifference to any theological issue, is also not an atheist - for such an adult is not challenging theism and not professing any views on the subject."
Critiques of God, edited by Peter A. Angeles, Prometheus Books, 1997.
Here's a link to some thoughts by a modern philosopher, John S Wilkins, that you might like:
Definitions of atheism | Evolving Thoughts
"“Atheism” is historically defined as the denial of
some specific deities. When Hume was called an atheist by his contemporaries, it was because he rejected the orthodox Christian God and religion; he was most likely a deist, someone who believes in a deity that is not directly involved in the ordinary affairs of the universe."