Can anyone explain the difference ( if there is one) between the caliph and the mahdi?...Why didn’t Al-Baghdadi proclaim himself the Mahdi?
The Caliph is the head of state of the Caliphate.
The Mahdi is the Redeemer of Islam.
It’s sort of the difference between the Pope and Jesus.
If you haven’t seen this video, it explains a lot about what is taking place regarding Islam, the Caliphate and the Mahdi.
https://www.youtube.com/watch?v=uY20IFaWlsQ&feature=youtu.be
Also, Walid Shoebat’s site has an article up about why Al-Baghdadi can’t be the Mahdi or at least would not be the best “fit”. http://shoebat.com/2014/06/30/emerging-caliph-iraq-antichrist/