The OTL standard example is, of course, Lebanon, and while not official to the same degree, many elements of that are present in Iraq after the US invasion (to be fair, some features of Lebanese confessional system are not actually enshrined in law, as opposed to entrenched political tradition and compromise). You could argue that Iran is a confessionalist state too as well as the state is constitutionally ruled on the basis of a version of Muslim Shiite doctrine while some religious minorities have a protected special legal status in some matters and reserved political representation while enjoying, in theory, the same political rights as anyone else. But these minorities are fairly tiny. I understand that, while it has a very strong ethnic dimension, the legal distinction between Malay Muslim Bumiputra and Indian and Chinese immigrants in Malaysia could be construed as a form of confessionalism, at least in some periods.
A similar argument, while things are a lot less official there, could be made that Israel has elements of a confessionalist system as well.
Syria is a plausible place for such a system to arise, even more so if you have a Greater Syria that includes Lebanon. And independent Kashmir or an independent, united Bengal also seem realistic places where confessional indentity could end up being officially enshrined in politics. Also, maybe, Ethiopia and Sri Lanka.
