I like that phrasing. I discovered it while reading Mere Christianity by C.S. Lewis. (What an amazing mind!)
Passengers and Parasites are words Lewis uses to describe two types of people the church cannot afford to have as members. Passengers just sit there and hold on for the ride. Parasites drain the resources and give nothing in return.
Unfortunately, the church has too many of both. Could it be the fault of leadership? Cheap salvation? We are a community that has open arms for everyone, but it seems there must be accountability and expectations for the true follower. When I think about passengers and parasites, I don't even consider new people or those who have never made a commitment to follow Jesus.
What I think of are people who should really know better. People who have "been saved and sanctified." These are the ones that feel they can ride along with no commitment to the mission of the church (either the local church or the Church), or they feel entitled to benefit from the ministry of the church. The Entitlement Mentality drains the church's meager resources away from reaching the lost and caring for the poor and downtrodden.
I think it is possible for the church to be a place of grace, with open arms for everyone, and still be a place where people are held accountable for their commitment to follow Jesus. Those who have been part of the Church longer should have much more expected from them. They have the experience, the understanding, and the insight to lead the church. They are given the responsibility to lead in such a way as to fulfill the mission of God to transform the world--not make ministry about fulfilling their spiritual needs.