Grimma, a bit upthread you said that churches should only be able to claim charity tax relief on aspects of what they do that are genuinely charitable an not 'self-serving.' Sounds fair in theory...but in reality, how do you decide which is which? Some examples:
A church has a pastoral visiting group. They go and see elderly members of the congregation, some of whom have Alzheimer's. They may well encourage them to go to the doctor, or even take them to appointments, or take them shopping. Their visits make it possible for elderly people to live in their homes for longer, and to avoid nursing homes. Is this charitable or self-serving?
A vicar has taken a funeral, and makes repeated visits to the widow of the deceased. Neither the deceased nor the widow go to church, but the visits give the widow the opportunity to talk and to work through her grief. Is this charitable or self-serving?
The church runs a community cafe, into which the local police officer pops every now and then to talk to people and help with any problems. It's a mixture of church and non-church people who go, and not a week goes by without someone being helped in some way or other. Charitable or self-serving?
The church runs a Bible study group. In the course of this group's study, people open up and share all sorts of problems and pains, and find peace and healing. Charitable or self-serving?
Someone with untreated mental health problems goes along to this group, and is persuaded lovingly to seek help, and is supported by the group for years, and in turn becomes very supportive of others.
Do you see the problem? These things happen in churches all the time. IMO whether something is 'charitable' or 'self-serving' depends primarily on the attitude of the person involved. But most of the time, the things that churches do can't be neatly categorised into one or the other. Ideally, everything a church does should be charitable as charity just means love. How do we assess that for tax purposes? 
Most churches run on a shoestring (in the C of E anyway), so to limit what they do by taxing them more heavily would reduce what can be offered to the community (e.g. the midweek communion service has to stop because the church can't afford to heat and light the church any more. The needs that were met there have to be met elsewhere, nearly always at a greater expense to the taxpayer, e.g. counselling). So keeping churches doing what they can do to meet the needs of others is good for everyone, whether you're a churchgoer or not.