[grimfang999]

Edit: too lazy to swap, but muddled Atheism and Agnosticiam somewhat

Im afraid, in what you are describing is not Atheism, but nihilism.

Agnosticism is being uncertain or disinterested in there being a God, but is accepting that there could be.

Atheism is the belief that there is no God because there is no scientific evidence of God. Should proof of a God be shown, they are willing to follow. You are also missing the point of the term. Theism translates into god, monotheism is a belief in a single god, while polytheism is many. You also keep confusing 'religion' with faith. Religion implies a collective group following a particular set of spiritual beliefs, while faith is the beliefs of one person and one person alone. While you can use language and throw it around to make the claim that Atheism's a religion, it is more putting your faith in science and science alone to find the answers.

Atheists and agnostics would take morals either as a cultural construct or a biological instinct, such as we will not kill a member of our own tribe/family unless it is necessary.

Nihilism, what you are descibing, is the absolute belief that nothing beyond what is physically here exists, there is no moral vitue, and everything we do is fundamentally pointless. There are even more extreme subgenres of this such as antinatalism, which states we should stop having children because it only causes more suffering.