When you notice that time progresses by addition, it is clear that time cannot be infinite. So, there is a beginning of times. From there, it is not a stretch to say that there must be a first cause at the beginning of times, which is the principle of causality to everything else. In that sense, subscribing to a first-cause theorem is a very rational point of view. You will also find this rather abstract first-cause theorem in Aristotle, Physics, book 7 and 8. Hence, first-cause beliefs are absolutely rational. People will naturally come to the concept of a first cause, i.e. a creator of the universe, just by experiencing how the phenomenon of time works.
The problem is not what atheists believe about the abstract first-cause theorem. They obviously believe what they want. The problem is rather a political one. We believe that there cannot be any other legitimate source of freedom restrictions than external ones. No such freedom restrictions can legitimately be man-made. It is forbidden onto humanity to redesign its own blueprint and invent new freedom restrictions to that effect. Humanity did not originally design its own blueprint, and therefore, is not qualified to modify it.
Atheists do not just believe that there is no first cause, which is otherwise their god-given right. Atheists also believe that politicians can invent and enforce new freedom restrictions. That particular atheist belief is very conflictual and utmost detestable. In that sense, yes, I totally agree that atheists and their politicians are detestable individuals whom we must combat by all means at our disposal. Atheists and their politicians are enemies whom we are seeking to defeat, no matter what it may take. Atheists and their politicians will learn the hard way that you cannot liberally invent new freedom restrictions and impose them onto others, regardless of whether they believe in a first cause or not, because that is irrelevant in this matter.