Radiometric dating merely measures the time elapsed since the material's clock was last "reset", whenever that happened or however it came about.
For example, Carbon-14 with a half-life around 6,000 years is useful to measure back about 60,000 years ago.
Other radiometric materials with half-lives in the millions & billions of years can measure back much further.
Naturally, if you reject, as you say, "unprovable assumptions", then you won't accept their conclusions.
However, those assumptions are reasonable and their conclusions consistent across dozens of measuring methodologies.
That's why from a scientific perspective they are pretty convincing.
But your taunting with "the altar of darwin" is uncalled for, since science strictly defined is the opposite of any religion.
The only thing you need to overthrow even the most "settled" scientific idea is confirmed data or better ideas which falsify it.
Insults carry no scientific weight, FRiend.
sorry, fake science carries no scientific weight either my friend. now, back to your Humanist Altar.