Not gonna lie, the theories for why people think it was fake is very interesting.
http://www.apfn.org/apfn/moon.htm
Watch the videos on the link, starting with the second video on the page. Combined they're like an hour long.. But yeah, it's interesting.
Personally, I think we were on the moon. They were still able to see the flags put on the moon decades later. So obviously someone was on the moon putting the flags there. But the flags they saw were all white, probably because of the sunlight. However, I wouldn't be surprised if NASA edited some of the pictures or videos