The IRS's Audit Techniques Guide states on page 14:
https://www.irs.gov/pub/irs-utl/ministers.pdf
"Ministers often pay a small annual renewal fee to maintain their credentials, which constitutes a
deductible expense.
However, ministers' contributions to the church are not deductible as business expenses. They may argue that they are expected to donate generously to the church as part of their employment. This is not sufficient to convert charitable contributions to business expenses.
The distinction is that charitable contributions are given to a qualifying organization
(such as a church) for the furtherance of its charitable activities. Dues, on the other hand, are
usually paid with the expectation that a financial benefit will result to the individual, as in a realtor's multi-list dues or an electrician's union dues.
A minister's salary and benefits are not likely to directly depend on the donations made to the church. They may still be deducted as contributions on Schedule A but may not be used as a business expense to reduce self employment tax."