The Crusades ended 700 years ago and history has demonstrated that an armed force governed by religious zealots and purportedly conducting its action in the name of a Deity will suffer a well deserved defeat. International conflicts are driven by vital national interests and assessments of an adversary's strenghts relative to your own and your allies. When the concept of carrying out a Divine mission enters into the mix rationality and the art of applying military science disappears and, you lose. It's that simple.
I'm not prepared to place the lives of men and women under my command in jeopardy for what some civilian like the current day TV evangelists and religious fanactic consider to be a holy mission. I'll leave the "mission from God" to John Belushi and Dan Akroyd as in The Blues Brothers. I'll agree to stay out of Dr. Dobson's faith of money raising and tape sales business but he, and his colleagues, must stay out of the business of conducting military operations or the underlying decision to enage in conflict.
but to institutionalize or endorse anything of that nature from any level of command is abject stupidity.
On a personal level, we should be free to discuss and advance our religious views. Doing so from a position of authority (ie, if I'm the CC and have a large religious poster on my office door) is another matter.
I'm more iffy on emails - I get emails daily that don't involve work per se - notes from friends and former co-workers (mostly jokes)...sometimes will send out something with religious implications to a handful I know will accept them as a note from a friend. I view this as a form of networking - I'm surprised at how often I'm working a problem and can go, "Wait a minute - Joe said something about that project..." and get some info to break the logjam. But when it comes to religion and politics, it pays to be careful - offense taken in these subjects carries a lot more potential for anger.