These are excellent examples of poorly constructed arguments.
"Atheist believe/contend..." Scientists make assertions about science. Atheists make assertions about belief/disbelief in god(s).
There is no point in responding to the content of fallacious arguments, other than to break them down to demonstrate their errors. These assertions prove one thing, in this case anyway:
Something can't come from nothing
Something = Sound Conclusion
Nothing = Fallacious propositions