Here's a list of figures common to the Muslim and Christian scriptures. In each case, like a photoshopped picture: the same figure, but with features missing, added, distorted.
God (Allah; same word used for God by Aramaic, Syriac and Arabic-speaking Christians and Mizrahi Jews, Alâhâ)
Aaron (Hārūn)
Abel (Hābīl)
Abraham (Ibrāhīm)
Adam (Ādam)
David (Dāwūd)
Elijah (Ilyās)
Gabriel (Jibrīl)
Isaac (Isḥāq)
Ishmael (Ismāīl)
Jacob (Yaqūb)
Jesus (Īsā)
John the Baptist (Yaḥyā)
Jonah (Yūnus)
Joseph (Yūsuf)
Mary (Maryam)
Miriam (Mūsā's sister)
Moses (Mūsā)
Noah (Nūḥ)
Satan or Devil (Shayṭān or Iblīs )
Solomon (Sulaymān)
Identity? No. But points of comparison. Maybe like a photoshopped picture of the same entity, yet comprehensively altered, warped. Nobody--- certainly not Pope Francis --- would say they were identical.
...but that wasn't quite the issue...forthere wasn't the claim that the new pope said they were "identical"...
However, he did say;
Islam is a syncretist religion consciously created by its founder to solidify his military conquests. It has elements of Christianity but somewhat changed to further Mohammed’s needs (Jesus as a prophet and Mary as his mother), elements of paganism (the meteor in the Kaaba with its embarrassingly vagina-shaped hole, evidently worshipped by the pagans of that region), and a confused version of Mosaic ritual law, which gave Mohammed total control over people’s lives. And it was iconoclastic, so Mohammed, by destroying visual references to the pre-islamic past, was able to erase it.
Finally, it was spread by force: unlike Christianity, it was never preached, demonstrated and voluntarily adopted.
There are many people in it who probably honestly want to be good and love God, but don’t know any better. So we can’t blame them. But as a religion, it’s a phony.