If there is a shortage of qualified religion teachers in the US, why not simply hire British RE teachers? They can teach based on my ex-girlfriends course and my experience in training RE teachers Christianity, Islam, Judaism, Buddhism, and Hinduism and also generally have a knowledge of Chinese and African traditional religions, plus can do stuff like "do science and religion conflict?" and sicuss bioethics etc, etc to contextualize it.
My A level course taught me Biblical Crit & The Quest for the Historical Jesus, Feurbach, Nietzche, Kierkegarde, Hegel, Freud, Marx, Christianity & other religions (Hick mainly), the Victorian Church and lost of other fun stuff. If bias is an issue we have plenty of atheist, Muslim, Jewish and Hindu RE Teachers here - and a good few Wiccans which never ceases to amaze me. I think the majority of RE teachers i have met have been atheist or agnostic though, with Christians representing the second largest group. Still they are definitely extremely well trained, and higher wages in the uSA would attract them?
cj x