Absolutely not, i would never work for any organistion that i consider to be evil and exploitative
It depends on what you mean by religious organizations. Are you include organizations with a religious board of directors? I've worked for many different types of companies and have noticed that the holidays defined as days off (about 8 a year plus 2 floating) can be defined by the board of directors. Jewish boards don't include Easter (Good Friday), Christian / Catholic ones do. If you mean churches or health care facilities, no -- I would not work for them.
It depends on the organisation. There's a Christian organisation based near me which bakes (very nice) bread and uses the money they make to buy and distribute food to the homeless and poor, for free to those who can't afford anything and for much less than it costs in shops to those who can afford a little. They help anyone in need whether that person is Christian, any other religion or not religious, and don't take employees' religion (or lack thereof) in account either - I know three people who have worked for them, one Muslim, one atheist and one Hindu. They also pay the "living wage", which is a recommended amount per hour a person is estimated to need to be able to live on without financial hardship and higher than the legally-required minimum wage, and while they do have a prayer meeting every morning attendance is strictly by choice. I would work for them, and did in fact once apply for a job with them.
On the other hand, there are numerous religious organisations that try to "encourage" (or inflict, depending on your point of view) their chosen religious structure on employees. There's no way I could work for one such as that.
I don't want to support a religious organization.
I have worked for Quakers, Catholic Workers, Presbyterians for peace in Palestine and the Rainbow Coalition with Rev Jesse Jackson