Talk of "the church" seems to be rampant these days. So it's useful to review what Luther and the reformers had to say on the subject
In the 1530s Luther devoted quite a bit of time and energy to reading, thinking and writing about the church. One of the results of this was a massive treatise, "On the Councils and the Church" (1539). In it Luther addressed the question of where "such Christian holy people are to be found in this world?"
He listed seven signs by which the church, the Christian holy people, are to be recognized:
Luther was well aware of accusations that he and his followers were causing schism. Writing in the "Smalcald Articles" (1537) Luther answered Roman Catholic opponents who claimed that they were the church and that Luther and his followers were schismatic:
We do not concede to them that they are the church, and frankly they are not the church. We do not want to hear what they command or forbid in the name of the church, because, God be praised, a seven-year-old child knows what the church is: holy believers and "the little sheep who hear the voice of their shepherd." This is why children pray in this way, "I believe in one holy Christian church." This holiness does not consist of surplices, tonsures, long albs or other ceremonies of theirs that they have invented over and above the Holy Scriptures. Its holiness exists in the Word of God and true faith. (Part III, article 12)