In order to claim mileage for a self-employed person, they must be traveling between two places of business.
Often this would include miles from home to a workplace if there is a qualified home office for the business. If there is not a qualified home office, then driving to the workplace is considered to be commuting miles and would not be deductible.
Given the situation you described, your miles from home to church would not be deductible if all of your work is performed at the church.