We are all beautiful, we are all human, we share this wonderful earth with each other. Faith transcends color. Life transcends color. Why should we allow the tone of our flesh to determine what we can and cannot do?
I agree with Myrkr on this. And quite frankly, the gods and spirits will choose who they will, and probably don't appreciate being told who may or may not honor them. However, I also understand that not all religions are universal, and that some have a more or less strong emphasis on ancestry and tribe.
Thousands of years ago, probably all religions were that way, being the beliefs and rituals and myths of specific tribes and bands. I asked my friend Beth for her take on this subject, since she studies Ifa and is involved with Esu, Yemaya, and Osun. We talked for about 50 minutes, and here's what I've distilled from our talk. The following is my words, but I checked and repeated the following no less than 5 times to Beth, and she OK'd it:
Blood plays a big role because the Orishas, etc. are deified ancestors.As such, their descendants can be considered to have a pre-existing connection to them.due to the belief that one's ancestors will watch over you.If that pre-existing connection does not exist, then one can still practice the religion,BUT there needs to be plenty of study and feeling the presence and uplifting fromsaid Orisha or whatever. A real relationship, a real spark. Not "puppy love". If that relationship if there, then nothing that anybody says or thinks can destroy it.It's possible to honor the god/Orisha, without having to convert to a religion, etc. You need to know the mythology and the gods.Everyone is a lightbulb, not the light. The light is the truth, we're just the lightbulbs. We're the radio, not the signal, people's own notions,etc. can and do get mixed in. It's like a game of telephone, and you should always take what anybody says with a grain of salt. It's not Gospel, so to speak.
Aside from the part about blood and deified ancestors, it's the same for any path or deity anywhere. Without study and true experience, even something as simple as feeling Ra's presence at a sunrise, your relationship with the deity, or practice of a religion won't amount to much. I emailed the leader of the aforementioned Voodoo workshop, Lilith Dorsey, about this issue, and await her response. I pride myself on researching and on getting things down in writing. :)
EDIT: I haven't gotten an email back, and at this point, don't expect to.