-Radiometric dating methods from Uranium-235/Lead-206, Uranium-238/Lead-206, Potassium-40, Rubidium-87, Samarium-147, Thorium-232, Rhenium 187, Lutetium-176 all agree on an approximate 4.6 billion year old earth (or all they all, each with different half-lifes, equally in error).
Basically, is this not simply saying that, if there were time, at the known rate of decay, this is how long it would take or did take to decay? This assumes that there always will be this decay, rather than, one day, there will be no rate of decay, as the bible indicates in us, and the sun, etc. lasting forever. So, bravo in men's ability to realize how fast we are decaying, and the universe around us, it means nothing for the future, or far past, as you must well know, and could not begin to prove, cause it just ain't so!
-Light from galaxies farther than a few billion light-years away indicate the universe is older than a few billion years.
Light in our universe we know also has a speed, or rate, at which it can travel, however light has been recorded in the bible like the stuff that predated the sun's creation, that need not be restricted to the properties of our present light. Only by assuming light is only the kind we now have in our physical universe, and always will be, could we arrive at your believed old ages! Adam saw the stars, it didn't take long ages to get here, so we know it was different then. If you reject the bible, then you are welcome to believe what you will, but could not prove in any way that today's physical universe light you perceive was always all there was. So all you have on offer here, in present speeds, and decay rates, is present rates and speeds, and a baseless belief it must need apply to a future and far past, just cause you say so, and want it to, but in utter absense of any scientific evidence!