My “goodness”, that sounds pretty serious. Opps, was that euphemism a blasphemy? What about someone saying “Doggone it”? We all know what it stands for.
Oh I read it very carefully. Indeed you did not specify a “second to second” knowledge, it was, however, implicitly included. You need to know
every act to “know if the atheist did something that
NEEDS to be repented”. After all, if one does not do anything sinful, there is no need for repentence. And there are billions of human “beings” (according to the catholic definition of human beings) who all die without ever committing any sin… either venial of mortal and who never reject the grace that God allegedly extended to them… and their “fate” is still uncertain.
An atheist - by definition - is unable to “repent”. In order to repent one needs to be religious. So according to your argument all atheists are hell-bound. I don’t think that this is the official teaching these days. I wish there would be an “official” teaching on this subject, something definitive.
I am aware of this teaching, however it has been “watered down” to irrelevancy. One does not have to be “catholic” in order to be considered to be “inside” the church any more.

There is also baptism by desire and baptism by fire… and who knows? there might be others. I wonder if you are aware of the difference between “denying God” and “denying the arguments for God”? An atheist is unable to deny God, he or she is very much capable of denying the
concept of God, and these are very different denials.