> I don't see how millions of years is compatible with creationism, while hundreds of millions of years isn't. God is omnipotent and immortal, so He could have decided to wait hundreds of millions of years before zapping life into existence.
True He could have, but the point of early life was to 1) transform the environment and 2) provide biodeposits as abundantly as possible. The Bible (Genesis 1:2) seems to imply that God was busy doing something valuable in the early oceans, and creating first life quickly is an obvious interpretation of that. Therefore, an old earth creationism model would reasonably predict life as soon as the earth could possibly sustain it.
I agree that hundreds of millions of years of nothing would not necessarily falsify creationism completely, but it would add more complex 'why' questions. Why would God wait so long?
> I don't see how this would be out of character for a deity who spent 1/7 of his creation time resting. (From an old earth perspective, that's hundreds of millions of years, right?)
For one thing the days are not necessarily the same length, for another thing, most OECs see the seventh day as being in progress now (Hebrews 4 implies that we are still in God's rest). This seems to be corroborated by the record. Throughout the last tens of millions of years, quite a few new unique species came into existence. But ever since modern humans arrived (which I would say began God's "rest"), there has been relatively little formation of new species, and those that have formed could probably be explained through evolutionary theory (which I do not entirely reject). In other words, while God was creating, new species that would have a hard time evolving were introduced; now that God is at rest, evolution is all we have to go on for new species.
And that is also something that can be studied and falsified. Will future studies show that during the last 100k years, the speciation rate was about the same as for the previous 10 million? If so, that poses a serious problem to a creation model. If future discoveries continue to back up what I said, the Biblical creation model gets stronger.
> In other words, hominids shouldn't share any of our DNA.
Actually, common DNA and other biology are about the same between humans and nonspiritual animals simply because this is the design that works. God doesn't have to do too many crazy things like that to prove His existence (I think He has already done more than should be necessary for that.