One problem that arises is which churches do we give the money to.

Is the Church of Satan eligable? How about Hawaii Cannabis Ministry" That ought to get some support here. There's one called Demon Church, http://demonchurch.com/ and the picture of their deity below is from their website. In my opinion, the mainstream churches are no more eligable than the Demon Church, and similar organizations.

The First Amendment to the U.S. Constitution:
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

The First Amendment to the United States Constitution is a part of the United States Bill of Rights. It prohibits the federal legislature from making laws that establish a state religion or prefer a certain religion (the "Establishment Clause"), prohibit free exercise of religion (the "Free Exercise Clause"), infringe the freedom of speech, infringe the freedom of the press, limit the right to assemble peaceably, or limit the right to petition the government for a redress of grievances.
First Amendment to the United States Constitution - Wikipedia, the free encyclopedia