Uh, you select the lens, then click on the thingy under the city bar (or not if you just want an overview of who pressures where) and then you look at how many followers there are for every religion? And if you want exact details, you hover over the pie chart and read the tooltip which explains you how much lifetime pressure every religion has put on the city?
I don't see which part of that is crap or unreadable... If anything it feels super easy to use to me.