I'm dissapointed that there's another civ with a religion unique. Religion is a gameplay system that is all in or nothing. If you invest into faith, you want to get the most out of it. There's no way to just go "halfway" there to get a specific bonus. Since it's a fight/investment to staff (?) off all those foreign missionaries, you can't just sail along.
It's hardly all or nothing... You get 4 bonuses (equivalent to 4 social policies), and 1 enhancer of your choice (defender of the faith obviously, if it's available) for establishing a religion, spreading it to your 3 other cities for peaceful Tradition game (and maybe passively to a couple of neighboring CSs or cities of a non-religious civ.) That is: ~30 faith for the pantheon, ~500 faith for the first two great prophets (another 500 faith for a great deal on your 3rd great prophet). This is a total of ~500 faith (equivalent of 500 gold, or half of a GP however you want to look at it) for 4 social policies of your choice, as opposed to 3 social policies of someone else's choice. For a total commitment of 500 gold or half a great person? That's a ridiculously good deal.
Religion ALWAYS pays off in terms of opportunity costs (not to mention you get to build the Grand Temple, which is amazing for tall empires, only if you have a holy city). Going all-in on religion is a strategy, and it will pay dividends, but there's no need to do it for religion to remain effective, especially if your empire's faith output cannot compare to the AI's (say, if you're going tall peaceful).
I typically do not play a faith-based civ, and on Immortal, I can still guarantee a religion with 4 total buildings (shrine + temple in capital and 2nd city) and not using a faith-pantheon. The first shrine you'll want anyway for the cheap pantheon, so it's 1 more of the cheapest buildings, and 2 temples worth of hammers. I don't have any problems with keeping my religion alive in my civ, and I don't try to spread it to any civ who is not both a) neighboring me, and b) does not have a religion. At most, if a religion civ starts next to me and he's turning into a great neighbor, then I will build one inquisitor and move him around to block my ally's missionaries (while not giving him open borders).
The religion is very helpful. Arabia's bonus, with certain founder beliefs, will pay even more dividends, without the requirement of religion spread or diplo penalties (Peace Loving, Tithe, World Church). Very nice.
Arabia is now an empire with all bonuses (Bazaar, Trade Routes, passive faith spread using trade routes) geared toward going tall, instead of wide. It's a huge change, but very synergistic.
