I'm not too sure what to think of it.
I feel like if you're tall, you don't need the religion spread, and the faith comes at the exact moment it is least important in the game, after you found a religion.
If you're wide the faith isn't worth the hammers and..you still don't need the religion spread because low pop cities under pressure from several sources change over quickly enough as is.
I feel like to make an impact, it would need to come a bit sooner and not require a religion. It also needs a different perk I'd say. The area around a holy city tends to be strongly religious anyway, and at 8 faith, I'm not sure it would ever be worth it to build it except in an empire tall enough as to almost guarantee not getting a religion anyway.