I believe that religious charities play an important role in Britain's public life. The advancement of religion is one of the oldest charitable purposes.
Across all charities, a very small proportion may not comply with their legal obligations. It is up to the independent Charity Commission to ensure that all charities comply with the requirements of charitable status. The Commission performs a vital role as the independent regulator and registrar of charities in England and Wales. I have complete faith in their ability to regulate robustly to ensure that the public can support charities with confidence.
The Charity Commission has published guidance to charities to assist them in relation to the advancement of religion for a public benefit. It explains how public benefit can include the provision of spaces for worship; the provision of public rituals and ceremonies; contributing to children's education; promoting social cohesion; relieving poverty; contributing to good mental and physical health; and providing comfort to the bereaved.
I would suggest you should contact the Charity Commission directly if you have concerns regarding the activities of a specific charity.