1)
:: Do you think that science can only deal with things that we observe?
: Directly observe.
:: Believed to be.
: For good reason.
: We don't need to directly observe something to be reasonably sure that it
: happened.
: There is no such thing as a direct observation: there are only conclusions
: based on interpretations of sensory impressions.
: In an attempt to avoid being too certain you have devalued what we do know.

So which is it? You do not know the big bang occurred, because you did not directly observe it. You are "reasonably sure" that it happened, because the observations you make now are interpreted to fit the pre-existing supposition that it happened.
Surely you understand the difference - exactly the difference between direct observation of something and explanation of something by incorporating observations.

: Are you ignorant of the big bang theory or do you deny it?

I have denied nothing. And you are once again making an effort to label me as a fool for explaining logic and observation. Even though I have not and will not and can not ever say what you want me to say - that the Big Bang never happened - you hate the fact that I'm simply saying the Big Bang (which you brought up) is not an observed phenomenon, only that what we do observe is interpreted to support the theory that it did happen. Why? No "reasonable" scientist will say we have observed the big bang. Hey looks like we're getting into "no true scotsman" territory.

2)
: We have the
: microwave background radiation and direct observation of the spectra of
: distant stars.

Indeed, those are observations - of microwave radiation and spectra of light arriving at earth from points in space based on a "reasonable" assumption that the light has traveled that way for its entire life.

: And in astronomy we have the advantage that we can look back in time to see
: the state of the universe soon after the big bang. So, in a sense, we are
: there.

Sorry, no. You ONLY observe light which can be assumed to have been traveling a certain amount of time based on the properties we know of light and a "reasonable" assumption about the makeup of space and time. You are not "looking back in time". That is your incorrect phrasing to describe what you are seeing. "looking back in time" is not scientific.

We are not traveling through a time portal. Our line of sight is not peering through a time portal. We are here, now, observing the end result of what can be "reasonably" assumed to be light that has traveled from a distant physical ball of burning matter, and we can even mathematically predict the location of that ball of burning matter, if we make "reasonable" presumptions about the history and life of those protons.

: This is scary stuff, you are in denial of the very basis of scientific thought.

I denied absolutely nothing except, only promoted critical thinking instead of blind acceptance of explanations for what has not been observed.

: And you sound like Ken Ham (and that is not good).

I know who Ken Ham is. I am not a supporter of his. Regardless, you're once again attempting to paint me a fool by association.

: You are throwing the baby out with the bath water. In an attempt to avoid
: being too certain you have devalued what we do know. You have come to a
: position were all assertions have to be treated the same. Nonsense now has
: the same weight as reasoned evidence and validated observation.

Once again, most definitely not.
I have seen people say science is about the search for truth.
I have seen people say it's simply about improving the human condition.
I have seen people say science is about many things.
It's dangerous to presume anything is truth, is it not?
It's just as dangerous to doubt the truth of everything, is it not?
Who's presuming what here?
As in a previous comment, I said science moves forward when practically feasible, whether or not something is "proven" to be true. On a case by case basis, we decide whether an explanation, which cannot be directly proven, is sufficient. Plenty of science is based on that process. Plenty of theories have been uprooted, and plenty remain strong, based on that process. No, to presume the irrefutable truth of any unobservable, unrepeatable explanation of events is a fallible position to hold. To move forward under the basis that it is considered, at present time, the best explanation, that is the choice scientists make.

: Have you seen the vital spark? If not then stop believing in it.

Did anyone before seeing the atom see the atom? No, scientists saw effects of a phenomenon they theorized as the atom until they saw the atom. Not seeing something is absolutely no reason to not believe it exists. On the contrary, it is reason to continue to seek out supporting evidence of its existence, until hopefully able to directly observe (and therefore prove) its existence. I don't need to see something to believe something, especially if everything I do see (which I now know) points to the existence of what I believe, and does not deny it.

: We have a set of rules that we use to try to delineate the two cases but we
: know that the rules are flawed. They don't work perfectly - for example:
: are viruses alive? But we understand the problems and find the effort
: worthwhile.
: I don't have access to a text book but the criteria are (roughly):
: metabolism perception (reacts to stimuli) motility reproduction

See the other links I provided in my previous comments. The article discusses the properties we use to define "life", and the attempts to create "non-biological life". You will find plenty of resources discussing the nature of life, and the difference between biological and non-biological.

: The rules are deliberately vague because we generally know it when we see it
: and it usually doesn't matter if something doesn't entirely fit. And note
: that the textbooks don't include 'vital spark' in the list.

You named it "vital spark" in this thread, not I. So it is no surprise to me if you can't find "vital spark" in any textbook list.
Do you admit there is a difference between biological and non-biological? If so, my case is rested. (which is NOT proof of this 'vital spark', in case you want to jump that gun again).