What makes a good church logo?

Our church is in the process of designing a logo (the currently don't have one). They had a few options at church on Sunday that a guy from a local sign writing company had come up with and Peter and I personally weren't impressed/happy with any of them (there were 4 different options, but all along the same lines). So we have been trying to come up with some alternatives. They want to use it for signage, letter head, and on the bulletin each week. So if you have any thoughts, suggestions, opinions that you think would be helpful, please comment!