>>212109392 (OP)Vagueish answer
Islam remains one sect localized faith to the Arabian Peninsula.I feel without a common enemy, Christianity would fracture more with multiple independent churches, although I donโt know much about Europe.
North and East Africa would slowly spread Christianity to their regions.
Iran would remain Zoroastrian, with migrating turks adopting that religion.
Central Asia would remain a mix of Manichaeism, Tengri, Buddhist, Zoroastrian, and whatever minority religion there is. Afghanistan would retain their sun worship. The Steppe too.
SEA would retain their mix of traditional faiths, buddhism, and Hinduism unless a new religion flourishes and establishes trade routes there.
Trade to and from the Indian ocean would be less since it was more interconnected due to islamic presence and their trade networks.
Politics wise, too much change to predict.