"the concept of "Umma" is very very similar to the "internationalism" of the communists: "workers of the world unite" and all that stuff."
Good remark. Socialism and Islam are basically isomorph or congruent in most of their ideology/theology to Christianiy. They is like all Sauron's minions in the Lord of the Rings dark and inferior copies of the real thing. Spiritually they are tools of the Enemy. The copy of the Ents are the Trolls, the Orcs are copied Elfs and the Southern and Eastern human allies of Sauron are the counterweights of the Wester and Northern humans. There is much in the Ring that reflects on the conflict between Western Christianity and Islam, I think. Laurence Auster on View from the Right has more of this.
Christianity, Communism and Islam are or proselitising faiths, recognising no race, border or territory. Islam and Communism are very agressive in their ideology were Chrisitanity seems to have a pacifist streak although it is just cynicism about the use of violence caused by the constant defeat of the Jews by mighty empires (Selucids and Romans).
When the non-Christian Jews rose in revolt in 70 and 135 after Christ the send emissaries to the Christian Churches who were predominantly Jewish and asked them to join them. The Christians refused and later took over the Roman empire seemingly peacefully while the Jews were expelled from Palestine.
By that time the non-Jews started to become predominant in the Church which was bound to happen to a detribalised ideology once it is succesful.
Basically one can see something similar getting underway in the US. The US has adopted a ideology of proseletising universal democracy. Any reference to the Anglo-Saxon roots of the nation have become unpronounceable. Invade the world - invite the world. The ideology of the US is too secular and materialistic to survive after the underpinning of military and economic power is stripped from it. And universal democracy is a contradictory ideology, any democracy, any nation, must have an ethnic core, otherwise it will not endure.