Make a distinction between atheism and extreme atheism.
That's a good question and worthy of some serious consideration not just for the purposes of answering your question but also for other more significant reasons that do not involve this forum.
As this thread has developed the terms extreme atheism have taken on more meaning, certainly more than originally intended or known about by me.
My take on it as of now...( subject to change in the future)
Atheism,
Normally atheism is a relatively benign belief system that simply states that the holder of such a belief holds no belief in the existence of a God. It suggest no violent or aggressive tendencies that could be intrinsic to that belief. There is no reason to hold a healthy atheist in any way as being wrong or deluded or anything of that nature as every one according to the Universal Charter of Human Rights (esp.article 18) which simply states that all are entitled to their beliefs. Article 19 which simply states the same for opinion and so on.
So atheism is just another branch of belief that in itself has no negative consequences if the rights of others are maintained and protected as per article 18 and 19 and so on.
Extreme atheism,
Atheism that violates those aforementioned rights can be classified as Extreme because the holder of such views refuses to accept other peoples rights to belief and opinion as they would their own rights.
In general terms Persons that instigated religious purges such as Stalin, Hitler, Mao etc would earn the title of extreme atheists. People who burn down churches, and slaughter religious folk because they hate religion (any) would be classed as atheist extremists.
In more specific terms atheist posters to this fora , social media etc who bully and ridicule people for holding religious beliefs would also fall under the extreme atheist label IMO.
***
Now to Secular Fatalism with its pre-determination.
Atheism,
Generally speaking, normal health atheism
does not rule out self determination nor freewill and are prepared to accept that humans are responsible for their decisions, choices and behaviors. It may be true that they question the reality which is actually a healthy thing to do. An atheist can allow a more objective stance on the topic of free will and determinism... which then allows more productive discussion and understanding to be achieved.
Extreme Atheism,
In the context of the above, Extreme atheists of a certain atheistic persuasion will rule out self determination and freewill by way of adhering to what is known as Secular Fatalism with inherent predetermination. This obliges them to reject the notion of freewill and self determination with the only alternative being that those
highly valued attributes of human life, welfare and self-determination, are illusions and a self deception, as no choice is truly available and that all is predetermined and unalterable.
The extreme atheist of this persuasion will promote it's belief as fact based purely on logic with out any evidential support and seek to persuade others to believe likewise by claiming it as fact and not theory.
As clearly demonstrated in this thread and in others, the ridicule and bullying tactics used to shut down productive conversation only goes to prove the extremes they are prepared to go to, to defend, as this thread seeks to prove, an indefensible position.
Extreme atheism in the form of secular fatalism/ predetermination, by it's own declaration that self determination is an illusion shifts responsibility for human activity past, present and future on to something else other than the humans in question.
It passes the responsibility for every thought, every action, every decision, past present and future on to a deterministic universe which then entitles that universe due to it's believed manifest ability to control human activity so thoroughly, a power only akin to that of a God.
So therefore logically,
Extreme atheism leads to a proxy God.
Which demonstrates
a fundamental contradiction in secular fatalism/predeterminism rendering the theory incompatible with any reasonable objective thinker.