In one's home church, one can certainly donate one's talents and time towards the ministry and that is admirable. I play for a church, however, that is not my home church. To me, a different scenario. If you expect a person who is not a member of your congregation to come and accept a position as an organist or MOM, you are expecting them to be there for rehearsals, at all your services, when the choir goes out on Sundays and during the week....basically, unless their home church has services that are not at the same time as your own, you are expecting them to devote their entire "church time" to aiding in your music ministry. Why would I not be paid?
"A workman is worthy of his hire" refers to preachers, musicians, etc....as in the Levites of the OT who were devoted to ministry within the church.
It is often said that musicians go for the highest dollar. Since I have accepted a position outside of my home church as an organist, I have seen a different light and "the other side". There are those who (on the other end) try to get out of paying musicians what they are worth. Case in point: Upon accepting a position as an organist, I voluntarily gave the church back $100 per week. It is 3 years later, and after two or three raises I have still not been raised back to the original salary. When I ask for a raise, I am usually promised one thing....and then an excuse is given as to why the amount agreed upon wasn't met (after the fact).
Bottom line...there are 2 sides to this equation. If you are playing at a church ESPECIALLY that is NOT your home church, you deserve to be paid for your time, gas, etc....