A charity may not have anything to do with religion or people. It may exist to promote a very narrow or broad interest. For example, a charity can exist to promote the work of an artist, or to promote art education in public school.
Charities, religious or otherwise, are often built around one or more of the spiritual principles enunciated by the Manifestation of God. There are charities to feed the poor, provide health care for the sick, shelter and education for the orphan, but they are not religious. They may be affiliated with a particular religion, they may be influenced by the teachings of a religion or the life of one of their venerated leaders, but they generally limit their scope of activity to putting into practice one or more of the tenants of their faith or their belief system.