Now then, BEFORE i start , let me clearly state i am a humanist agnostic, with atheistic leanings...
BUT..... i work professionally in a number of churches and other places of worship, on a regular basis... including St Paul's, (and Westminster Abbey, St Martin in the fields, St Bartholomew the great, St James's , all the regional cathedrals, etc etc , the list goes on) recording live events for broadcast on Classic Fm, and the BBC, and also, for classical music CD Album releases....
(This week for example, was recording a choral event , just round the corner from St Paul's, at St Batholomew the Great , in Cloth fair, just off West Smithfield... )
the running costs and maintenance of such buildings is astronomical, and in these days of reduced attendance, reduced income from collections and bequests , either they make what they can from the tourist, or the place falls down...
so.... no i do not think they've taken the christian out of christianity....
in the vast majority of places, access for private prayer is still free, (but wandering around taking photos, and saying oh gosh, is NOT praying... and the people running the place are NOT complete idiots ..... (okay, they have a bad case of religion, but other than that, they still have enough sense to catch out the cheapskate fee dodgers... )
some places set aside times of day for people to pray, others set aside non tourist access sections of the church..... but nowhere i've been charges the faithful to carry out the articles of their faith.
(frankly, I would...... but then i'm not one of them..... i'm a realist.... if you have an avenue to acquire legitimate funding for your survival, then use it i say..... )