I hang out in the student lounge of the physics department (or did last semester when I was in school), and those who would argue again the existence of God would use such arguments. However, I would like to answer the two statements you put forward (which I never heard either):
Ok, so this is your memory of the statements that were made. I suspect the summary you have given has been affected by your interpretation of the statements. You see this happen all the time online - someone makes a statement X, and the next person slightly modifies the statement while responding to it. When it's written online you can go back and reread the original statement to try and wash out the interpretative overlay, but you can't do this when you're going by memory.
The reason I'm pressing this issue is because an atheist who would assert "there is no God" would be called a strong atheist, and they are a tiny minority of atheists, as far as my experience is concerned. The vast majority of atheists I've interacted with are weak atheists, who don't assert something like "there is no God", but rather assert that they do not believe in any god. (atheists believe in one less god than you do)
Atheists tend to avoid making "strong atheist" statements because it is predicated upon proving a negative, and most atheists are aware of the problems in that stance.
150 years ago there was no evidence to necessitate the existence of quarks, but that doesn't mean that there is no such thing as quarks. It is okay at the time to say one did not believe in quarks, but the particle is a real thing. Furthermore, the statement itself is based upon a scientific process. Evidence is not deemed evidence to support a hypothesis unless it can be tested as such. Since things of spirituality are not testable by others to receive the same conclusion, then what may be evidence to one individual would not be considered as such to another.
The problem is that people have proclaimed the existence of God throughout all of human history, and anxiously attempted to prove that existence to skeptics. Were there any evidence that required the existence of a godbeing, it would be proclaimed by every believer on the rooftops. Instead, all we have are anecdotal experiences that also have possible naturalistic explanations. So to add the god component to the explanation instead of the naturalistic explanation is to add an incredibly complicated extraneous factor, which makes it highly unlikely.
In other words, people have been hunting down this particular quark (God) for a very long time with no success. Sooner or later one ought to admit that this lack of success means something.
Maybe I took it a step further than it normally goes, however, many will take that since the Bible is full of "errors" that it must be false, and since those who support the Bible support the idea of God, then God is probably false as well.. I for one see that creationism is describing evolution, so both are correct to me.
There are many, many people who are theists and believe in evolution, so I think this particular example of yours was very flawed and indicates that you are attempting to recreate what atheists said, totally by memory, and your memory is fallible. I am skeptical that atheists are running around making the assertions you attribute to them. I believe this is how you "hear" what atheists are saying, however.