I think religion is probably your best bet. First strategy that comes to mind for that is play as Byzantium and feign like you’re going for domination. It’s pretty easy to get a great prophet with Byzantium and you can convert the AI civs by warring with them (defeating enemy units as Byzantium converts nearby cities) so it wont be quite as obvious as going for religion with Russia for example. Then like others suggested stockpile faith and send out a huge group of apostles and missionaries at once to convert whoever wasn’t converted by war. It might reveal your hand a little but you could consider the missionary zeal belief to help speed up the missionaries and apostles. Also if possible getting suzerain of Yerevan right before you produce all of the apostles would would be good.