for the most part you judge the past by the way you see things operating today.
Well, consider that we have no reason to think that the laws of nature (things like gravity or radioactive decay) are time-variant. For every-day matter and for masses and length-scales relevant to life on planets (as opposed to black holes) is well-understood and is not dependent on time. An atom of uranium has a certain probability decaying in any given timespan, whether that timespan is now or a billion years ago.
Fundamentally, from the perspective of the physics framework of the universe in the form of the standard model, this is a fair assumption given that we have no reason to think time alters the model. Conditions might change with time, but time itself is not a condition.
If God exists, if He did the things described in the early chapters of Genesis, then we have reason to believe in a more catastrophic view of history.
Is the existence of God an assumption on your part? (After all, I'm sure you would agree with most Christians that the nature of God can't be known and that faith plays a huge role in your beliefs.)
Is the literalness of the stories in the bible an assumption on your part? We know that large parts of Genesis were borrowed and altered from earlier myths (and I use the term correctly here, since the Babylonians were aware their myths were not literally true) like the Enûma Eliš for example.
Creationists use a starting assumption of catastrophism when we interpret the evidence. Thus, when we see the Colorado River slowly cutting the Grand Canyon today we don't just assume it always has. We believe the canyon may have been formed more rapidly by a lot of water over a little bit of time - the flood.
If you assume a God exists and that this God is capable of making anything happen, then no evidence could ever possible show you're wrong. Any evidence you're shown can be dismissed with "Well, that's not a problem for God."
If I'm wrong here, please correct me! If there is any evidence that would make you reconsider whether you're wrong about the existence of a god, I'd love to know what form that evidence would take.
We both have assumptions when we look at the evidence - that is why this is not a debate over evidence.
Scientists have really only one main assumption, and that assumption has been repeatedly tested, and we have things to show for it. Planes fly and computers compute and medicine works - if our assumption about the universe behaving according to rules was wrong, then these advances would not be possible.
With creationism, you're assuming a god exists and that this god created the universe and that this god chose to intervene in the past and so on - many assumptions which you cannot test.
So to say we both have assumptions is to be dishonest about epistemology.
Both assumptions require faith.
I don't need faith to know that my electric razor will work the same today as it did yesterday. Don't use the word faith when you really mean trust. I trust that the laws of physics work the same today as they did yesterday and a billion years ago because of our understanding of them and the useful things and testable predictions that understanding gives us.
This kind of equivocation is why creationists get labelled as dishonest. I know you don't want to be thought of as being dishonest.