I don't understand that Religious Tolerance abuse. AFAIK, you can keep the benefits of the pantheon of the second most popular religion in your city, right? So, how can you have the same pantheon twice? I think I'm unaware of something, it has been a while since I don't play civ.
It's like this: (see my screenshot... my capitol is getting double bonuses from sacred path but this works on any pantheon)
Cities with a majority religion (OR PANTHEON) receives the pantheon bonus of the 2nd most popular (NON PANTHEON) religion.
I made one of my satellites (Sao Paolo which barely had any jungle
) my holy city, and hence religious tolerance does not work on it, BUT my capitol's people are mainly still pantheon-worshippers. Once my capitol gets at least one follower of the full religion, "Brazilian Pantheon" is still considered the majority "religion" as far as religious tolerance is concerned, but my "Eastern Orthodoxy" (which originates from Brazilian pantheon) is considered the 2nd popular religion.
Hence +1 culture from majority belief and +1 culture from religious tolerance. (being tolerant of your own religion
)
So basically if you took piety but failed to form a religion, if you at least have a pantheon, then religious tolerance is not completely wasted once AI cities start exerting pressure on you... however if they use missionaries usually this wipes out the pantheon so no luck.
Once Eastern Orthodoxy becomes the majority religion, the pantheon does not get considered as "second popular religion" however, so the bonus will go away with time (you can prevent this by growing your city two times faster than the religion spreads, but other AIs religion might come in eventually anyway, so this abuse is only for early to midgame. It would be nice if miraculously other religions never reach you and you have BWCs that are twice as effective at generating tourism though)
I don't consider this a cheat, more of an exploit, but for all I know this may have been intended on the dev's part.