It would definitely be taxable and I would worry about the IRS claiming private inurement if it was being included in his pay.
In my humble opinion it would be better to raise his pay to cover that cost and he could pay those expenses out of his own pocket.
dependent educational expenses by: Anonymous
According to ISS pub 15b http://www.irs.gov/publications/p15b/ar02.html
It looks like if your church gives this benefit for dependents it would be included as income in box 1 of W2. The Pastor may be able to claim if on their own, have them see pub 970.
You might see if it could be redone as "dependent care" if they qualify, see pub 503.
Prayers.