Let the Eastern Roman Empire collapse catastrophically before the Arab onslaught while Sassanid Persia endures.
Then sometime in 8th-9th Century, either Persia converts to Nestorianism (not very likely) or some nomadic Nestorian tribe like the Seljuk Turks (Seljuk ostensibly was Nestorian once) or the Mongol equivalent of that TL take over. Add a Nestorian Tamerlane equivalent and you have Christian Persia. Maybe some of the tribes can even go West enough to seize Anatolia and Constantinople back, as well as conquer the Levant.
Meanwhile the collapse of the ERE means Islam spreads unchecked into the Balkans and Southern Italy besides Spain. Slavs and Magyars convert after some time, and so do some sort of proto Rus. Europe degenerates into a long period of theological strife between Islam and Christianity, but eventually Islam triumphs. Then, thanks to negativity that comes from the Easterners coming a reconquering Constantinople etc, they forget positives about Prophet Isa and start thinking of him as the Great Other.
Of course, a lot of what I have said is borderline ASB and very very difficult to manage. This is not "for the want of a nail" scenario, everything must remain within a very narrow path (such as Islam not getting Hellenized to a point where it is effectively a Christian sect) which is not particularly likely.