"Holy Spirit is universal. There is one Light but many lamps; there is one Wine but the glasses differ"
(Abdu'l-Baha, Tablets of Abdu'l-Baha v3, p. 505)
Seeing as we strongly believe that all religions are the same in essence I think the name of the essense is irrelavant why would it matter what it be called?
In reference to the "new name" of Revelations, our dear Lord said that the new name has a spiritual and inward meaning, not an outward one, that it does not mean something that can be pronounced by the tongue, but it means that when a soul comes into the great Kingdom of God.
The "attributes" or "names" of God light upon him, and by this he receives new consciousness and new understanding, and he becomes a new man. Therefore "call all humanity to Islam" would in my interpretation be "calling humanity" to the "light"
Regards
PK