If the church calls us into service through the guidance of the spirit and by the authority of God then we are not called to volunteer (A volunteer is someone who gives themselves to something without expectation, it is voluntary, our choice.) If the church has the authority of God and acts under the guidance of the Spirit, then we are not being asked to volunteer but commanded to serve
Instead of worrying about what tomorrow will bring or what the future will be, what the church will look like, or when Christ will return, we have been charged with witnessing to the goodness and the gospel of Jesus Christ. That witnessing begins here in these pews, our Jerusalem. We are to remind one another, teach one another, point one another to Jesus, the cross. We are to remind one another that our hope not just for the future, but for today lies in Christ alone.