In this instance his religious affiliation is not grounds for action his behaviour is. In fact it is better not to mention religion in any written reports as this could be considered grounds for discrimination.
What is relevant is that although he has alot of knowledge he lacks drive and ability to motivate others.
As a director surely he could reschedule key meetings to ensure he is available the fact that he misses them but is not proactive is an issue. What is clear is that the job does not appear to be a high priority and this is manifested by his inflexible attitude to attendance. Does he expect others to work late to cover his absences? If so then this can build resentment. Is he unflexible about other people leaving for their commitments? Ask him what his priorities are and what is his vision for the department. What are his goals and plans, how does he cover meetings he doesn't attend? How does he communicate and motivate his department? As a director I would expect him to have vision and direction not just deal with day to day tasks. He should be improving the department and seeking to improve his skills as well. He should be communicating with other directors and coming up with ideas. The people who work for him will take their energy and perspective from him.
He is not a leader and therefore is unsuited to the role he finds himself in. He would be better in a singleton role where he has no subordinates.