For a form rejection, this one is actually not so painful:

Dear Author,

Thank you for your query and for allowing me to consider your work. Due to the high quantity of query letters I receive, I must be highly selective in requesting further materials to read. Unfortunately, I'm afraid I must decline on this project right now, but I do want to encourage you to continue submitting. Just because a project isn't quite right for me doesn't mean the right agent isn't just around the corner. I wish you the best of luck with all your writing endeavors and in the querying and submission process. Persistence pays off, so don't give up!

Still a rejection, though. Stay tuned.

Writer's Tip: Explore characters that aren't human.