In some religions, people accept upon themselves some kind of "mission" to do whatever act to help others. In many cases, it involves collections to send to the poor, or to 3rd world countries. The items sent are not themselves used for religious purposes, but the collection is part of a religious "mission."
Is it permissible to give something to someone collecting for one of these missions? Is it allowed/encouraged to help them with their own religious "mission?" If the status of the religion as idolatry makes a difference, please include that in the answer.
Assume that the items being given are otherwise going to be discarded.