Go Ahead and Get Out the Paintbrush
Can a very expensive statue given to a church be repainted without permission from the donor?
If the statue is truly a gift, then the donor gives up all rights to the statue. At that point, the statue belongs to the church, and it is the decision of the church to repaint the statue if that is deemed to be necessary. If a donor wants to maintain control over the statue, it should be offered as a long-term loan to the church and not as a gift—similarly, perhaps, to museum patrons who allow museums to display precious artifacts "on loan" from the patron's personal collection.