Let's take a look at his futile attempt to discredit atheism. If anything I say here is incorrect, please let me know... unlike the quoted dipshit, I'm open to learning new things, even if it means that my pride will take a bruising in the process. For the record, I do realize that time only began when the big bang happened, and that there was no real "before", but I needed to use time-related words to try to get at some of the concepts I'm discussing here. Anyhoo...
If matter and energy cannot be created, how did they originate?
Where did the entire physical universe come from?
So, matter and energy can't be destroyed within our current reality. Since our reality didn't exist before the big bang, you cannot apply its laws to the "time" before that event. Likewise, no one knows if the big bang "created" the matter/energy within our universe, or even what caused the big bang. All we know is that it happened (background radiation, movement of the galaxies, etc.), and it was responsible for the current reality we live in.
Some have suggested that anytime a black hole is formed, a new universe is created on the other "side", after a big bang event. Since black holes draw in energy and matter, that could possibly be one explanation for where everything came from. Not that this is anywhere close to having been proven, but at least we admit that we're not certain about everything, unlike you creationist nuts.
Why couldn't the universe have always existed?
Because nothing that has a beginning and an end could have always existed.
See above. Our reality's physical laws didn't exist before the big bang either, so no one is qualified to say what could and couldn't happen "before" the big bang.
If the universe is "all matter and energy", how could it be an open system?
If the universe is everything, how can there be something else out there to provide more matter and energy?
Circular logic and assumptions for the win. How do you know that our universe isn't actually a multiverse? Have you ever left the universe? No? Then shut the fuck up.
How could DNA and RNA evolve from something very rudimentary into their present day intricacy when the organism containing the basic genome would require the more complex, present day DNA and RNA to replicate?
DNA and RNA are made up of some very basic proteins, which were shown to come into being under the right conditions (see Miller-Urey experiment). These proteins weren't really 'alive', so they could still function and replicate themselves without intricate construction. The issue of survival didn't exist until AFTER that complicated DNA structure came together. Go read a textbook about abiogenesis... until you're properly educated in the basics of RNA and DNA, you won't be able to understand why abiogenesis is actually a very real possibility, under the right conditions.
Nobody has ever observed blah blah blah
We've observed plenty of evidence that led to those theories. You fail to understand how observation works.
Nobody has ever observed your Christian God NOR have they observed any evidence that lead them to accept that he exists. You fucking dipshit.
You fail at understanding how scientific theories work, go the fuck away and never talk about science again, you retarded jackass.