Employment at church

I've heard many times that Christians want to be cautious when purchasing things that could directly support the advancement of a false religion (e.g. Girl Scout cookies), especially if they are aware of where the proceeds are going to. Are there any concerns about that when seeking employment? Is there anything wrong if a WELS Christian served a non-denominational or ELCA church as a custodian, secretary, or groundskeeper?

Allow me to pass along a response provided to a similar question: A Christian may and often does seek or accept employment that in some indirect ways benefits heterodox groups as well as unbelieving communities. Seldom is this kind of activity an expression of doctrinal fellowship, nor is it perceived by people as that. A person’s conscience might factor into this, as we do not want to sin against conscience (Romans 14:23). Or if there are weak brothers and sisters who might be confused or misunderstand the arrangement, we want to be ready to explain and clarify and instruct — and possibly refrain from exercising our Christian freedom for a time for their sake. But we don’t want to unnecessarily limit our ability to love our neighbor and serve our neighbor as part of our vocation if we are able to do so without compromising the truth.