I think I can accept your "fact" of abiogenesis, if you would include the possibility of life having come from outer space as being one of the possible processes of abiogenesis.
Fact of Abiogenesis - Life did have an initial occurance on Earth"
Good point there. I hadn't even considered an extraterrestrial source. I guess that is certainly a possibility (reminds of one of my favorite episodes of Star Trek - TNG).....
I guess the fact of abiogenesis would state.
First part - "There was originally no life on earth" - In other words if you go back in time far enough at some point there is no life on earth. For example, let's say there is no life on earth for the frist 2 billion years (just an example, not a claim).
Second part - "There is life on earth now"... Basically at some point in earth's history life appeared and there had never been terrestrial life before that.
We may never have a theory of abiogenesis... who knows. (personally, I think our best bet would be to get really lucky and discover another earth like planet very early in it's development cycle).
However, if we are even going to try and figure out how life arose I think it's very important that we have evidence that there was once no life on earth and there is now.
Question: Do we have enough evidence to know that there was origninally no life on earth. in other words Start condition = no life.