God invites the Church to participate in his Mission of Reconciliation, both deed ("ministry") and word ("message").
The missional movement reminds us: "It's not that God has a mission for his Church. It's that God has a Church for his mission." God's mission of reconciliation comes first. God calls the Church to participate in that mission. We can describe it many ways (see Matt 28:18-20, Acts 1:8, Luke 4:18-19, 1 Peter 2:9-10, and others). What we do as Faith Church should help us as members of God's Big-C Church to participate in God's mission.
Our "Service Sundays" 2x per year help in this. Why? Not because they take the place of the restoration / reconciliation / witnessing that the Church is called to each day. No, rather because they model and inspire this sort of work.
So, as we go out and serve, let's consider how our activities might be broadened into daily acts of service. Or how our activities today remind us of other ways we can participate in God's mission of reconciliation and restoration and healing.