There's a single word that can be one of the worst or one of the best words to use in fundraising. The word?
Here's how to make it the worst:
When we means "those of us in the organization" or "the committee that wrote this message."
When used that way, it's exclusionary. It sets up the sense that we are an organization, not a person. That we are bigger and more important than you, a mere individual.
That's not good for fundraising. People don't give because you are big and important and awesome. They give because you give them an opportunity to put their values to work. They don't give to your organization; they give through it.