An individual stands justified before God by faith in Christ. He receives this faith through the working of the Holy Spirit through the Word of God and the Sacraments. This implanted faith blossoms into the fruits of good works in service to the neighbor.
But faith isn’t only about the individual. “Our churches teach that one holy Church is to remain forever. The Church is the congregation of saints in which the Gospel is purely taught and the Sacraments are correctly administered.” These two things—God’s Word and the Sacraments—are sufficient for the true unity of the Church, even though local traditions, rites, and ceremonies may differ from place to place.
This one holy Church is found wherever the Word of God and the Sacraments are being administered according to Christ’s institution and command, even if evil people and hypocrites are mingled together with them. For the Church is not a creation of man, a collection of like-minded individuals who discover that they have something in common, but a divine creation. The Holy Spirit calls, gathers, and congregates the Christian Church on earth, from place to place and from time to time, as it pleases Him.