Obviously, you are obligated by mortgage as one of the guarantors, so the real decision is based on your personal situation.  If you are leaving for personal reasons, and there is no reason to feel the Church is about to default on mortgage, then you don't have to do anything.  You cannot remove yourself without the Church refinancing building, and in this recession very few banks are even lending at this point, so you have to realize you are bound to obligation unless a refinance is completed.

Needless to say, the equity and payment history of mortgage should be known by you, so as long as mortgage is being paid properly, and depending on how many years are left on mortgage, you may not need to be as concerned.  If you signed personally, you are obligated, if you signed as trustee only, then this is different as this is similar to being officer of corporation, and if you leave company, you are not obligated, the company is.