If you don't really have any favored position, then you basically don't know. And if you don't know, how can you be so sure? All you seem to know is that God did not have a hand in it. That is faith based on a personal choice.
The 24 hour day thing is a non-starter. I am a fundementalist, but I am not taking the position that the bible teaches 24 hour days in Genesis One. That is an interpretation that is not demanded by the text. By the text, the eventh day is still ongoing. Chapter two says God did the work of the six days in one day! The phrase "Evening and Morning" is used in Daniel to describe the whole of the end times, a period of 3 1/2 years at the least. The New Testament says to God 1,000 years is as a day, and a day as 1,000 years. He is outside of time and this is just a smattering of the scriptures that strongly imply that the universe is far older than 6K years.
You are trying to argue against a position that neither I, nor anyone else on this thread holds. I could come up with some good arguments against a Flat Earth, but what good would that do? It is not a position that you hold.
Hindu cosmology does not stomp the bible flat when considering timescales, unless you hold to the most stompable interpretation of Genesis.