Can I include historical examples?
Manichaeism was very widespread and actively seeking converts in the first millennium A.D, to the point of rivaling Christianity but eventually died out.
Am I missing any?
Am I misunderstanding any?
Or when we talk about how "religion" always seeks to convert people, or conquer/colonize new places, or believe its way is the only true way... are we really only talking about Christianity and Islam?
Any religion that didn't evolve out of a culture/nation's paganism would have had to seek converts at some point or they wouldn't be the size they are today. Sikhism, Buddhism, Bahai and probably Zoarastrianism would fall into this category. Hellenistic Judaism was also fairly convert friendly IIRC.