The Church
What is the Church?
The Christian church is made up of those who have been baptized and thus have received Christ as the Son of God and Savior of the world. Sometimes it is referred to as "the Body of Christ." 
Lutherans believe that they are a part of a community of faith that began with the gift of the Holy Spirit, God's presence with his people, on the day of Pentecost. The church, regardless of the external form it takes, is the fellowship of those who have been restored to God by Christ. Indeed, to be called into fellowship with Christ is also to be called into community with other believers.
To Lutherans, who subscribe to the Augsburg Confession, Article VII of that document defines the Church:
It is also taught among us that one holy Christian Church will be and remain forever. This is the assembly of all believers among who the Gospel is preached in its purity and the holy sacraments are administered according to the Gospel. For it is sufficient for the true unity of the Christian church that the Gospel be preached in conformity with a pure understanding of it and that the sacraments be administered in accordance with the divine Word. It is not necessary for the true unity of the Christian church that ceremonies, instituted by (people), should be observed uniformly in all places. It is as Paul says in Eph. 4:4, 5, "There is one body and one Spirit, just as you were called to the one hope that belongs to your call, one Lord, one faith, one baptism." *
The church is essential to Christian life and growth. Its members are all sinners in need of God's grace. It has no claim on human perfection. The church exists solely for the hearing and doing of God's Word. It can justify its existence only when it proclaims the living Word of Christ, administers the Sacraments and gives itself to the world in deeds of service and love. ELCA Lutherans recognize a wider fellowship of churches and are eager to work alongside them in ecumenical ministries and projects, in response to Paul's description of the Church in Romans 12:4-5: "For as in one body we have many members, and not all the members have the same function, so we, who are many, are one body in Christ, and individually we are members one of another."
* The Book of Concord: The Confessions of the Evangelical Lutheran Church, translated by Theodore G. Tappert, 1959, Augsburg Fortress. Purchase this book.
Scripture quotation from New Revised Standard Version of the Bible.