Many second-hand items retain the imprint of their original owners, and may be sources of psychic trouble. Some religious items may be antipathetic to you. Some individuals are harmonious with one set of religious items, but ill-disposed to others. This only denotes that the person is somehow at odds with those aspects of religion symbolized by those items. Addicts, alcoholics and psychotics leave the worst psychic imprints.
Negativity naturally dissolves on the half-life principle.
This is the same manner in which radioactive materials dissipate. It is found in places and things infused with negativity. For Further Study This is only a basic introduction to magickal safety. It gives plenty of practical information.