This is actually a fascinating question, although probably not really a practical one as I doubt many churches would feel moved to sue a former employee over IP rights. But, given that, most employees for private and public companies give up IP rights as part of taking the job. Tech workers often can and do negotiate opt out clauses from such automatic granting of all IP to the company, but most don't or don't have the negotiating leverage. But Pastors and ministerial folks get real interesting. They are in that category of not really employees. This is actually how all the "star" mega-church pastors make the big bucks. They have the platform as the minister of the church, but everything they produce, even sermons given at the church, is their IP. They turn around and sell the IP in books for which the advance or any payments goes directly to the person.
This is one place where Rick Warren, unless he has changed, should probably be commended. When he sold a bazillion copies of the Purpose Driven Life, he first gave 90% and then 99% of the proceeds away. He kept enough to pay the taxes.