They probably have the trinity (or lack thereof) right. They probably have afterlife and hellfire (or lack thereof) right. They have Christmas right, even though Christmas has largely evolved into a family holiday, and people generally no longer care about or are aware about its pagan roots. Their total avoidance of it (not even acknowledging "Merry Christmas") is an extreme reponse.
They may have neutrality right in terms of religious involvement in politics. However, in terms of warfare, as long as evil exists, there is a need for a response to it.