Scientists accept an age for the Earth which is four and a half billion years. (See, for example, Scientific American v261 p90(6) August, 1989.) The two major branches of Creationism are Old Earth, which accepts the scientific answer, and Young Earth, which prefers an answer on the order of 6,000 or 10,000 years. There are a number of young earth arguments.
So, we aren't arguing about percentage points here. The decision is: thousands? Or billions?
These days, science uses radioactive methods as the primary way of dating the Earth. We could check if a radioactive method is consistent with the deeper-is-older rule, or check if several radioactive methods are consistent with each other. Or, we could find a different clock entirely.
However, we don't need a clock, just to know that something is old. One way would be to look for known astronomical cycles in the rocks. We could just count rock layers or ice layers. We could check if short-lived radioactives are found on Earth. Or, we could look at the question of stars being more than 10,000 light years away (in which case we are seeing light that is more than 10,000 years old). Of course, this light can be explained away (rather badly) by saying that starlight was created in transit.