I’m standing in the aisle for, like, ten minutes debating between “6000 is the new 5000. Happy Birthday!” and “And I thought 4,499,999,999 was old. Happy 4,500,000,000th Birthday!”
The debates between OEC (Old Earth Creationism), YEC (Young Earth Creationism), ID (Intelligent Design), and Theistic Evolution are heavy and heated most days of the year. Reddit is no exception. The following is a stellar write-up by Redditor crono09 who very succinctly explains all of these positions for the layman like me.
Here are some major categories in regards to Christian views on origins:
Young Earth Creationism (YEC) – The days of creation stated in Genesis 1 were literal 24-hour days. Therefore, the earth is young, probably less than 10,000 years old. Macroevolution did not happen, and the species were created more or less as they are now.
Old Earth Creationism (OEC) – Creation happened as described in Genesis 1, but the days weren’t necessarily 24-hour days. Therefore, the earth could be old, maybe even the billions of years accepted by mainstream science. Macroevolution may have happened, but if so, it was directed entirely by God. Humans were probably created directly by God, not evolved from other species.
Theistic Evolution – The timeframe supported by mainstream science is correct. The earth is about 4.54 billion years old, and species (including humans) came about through evolution. God likely had a hand in directing it along the way, but it happened in accordance with scientific evidence. He mostly set the processes in place and let nature take its course.
Of course, there is a lot of variation within each of these views. There are also some less common viewpoints on origins, and not all of them contradict each other, so there are people that hold a combination of several different beliefs. Yeah, it can get complicated. OEC seems to have the most variation in beliefs, which is why I included a lot of “maybe’s” in that definition.
Intelligent Design (ID) is a little different. It’s an attempt to take a scientific approach to origins rather than a theological one. It claims that there is evidence for a designer who brought about the world as it is today. The main evidence provided by ID is irreducible complexity. As such, ID is compatible with any other views above, although I believe that the people who first proposed it believed in theistic evolution. Essentially, if you believe that the scientific evidence supports the existence of a creator rather than accepting it only on faith, you believe in ID.
I hope this helps you put all these differing ideas of creation into perspective.