I would like to know your opinion

I am not an American but a Muslim (I don't know why I mentioned that) anyway. Honestly, I've been reading, watching and commenting on the 9/11 attacks for about 1-2 months now. I just watched the September clues documentary. So I'm curious about your views, what do you think about this topic? do you think it's really a lie or the truth? what is shown in the videos seems close to the truth (conspiracies), but in some 9/11 attack videos they write things like “my cousin was on the plane, I miss him, those who say conspiracy are mentally retarded”. Honestly, I am in between and I would like to know your opinions. My English is not very good so I hope I have made myself clear.