Fan or Follower - Essentials Intro
The church is the community of all true believers for all time. This definition understands the church to be made of all those who are truly saved.
In its true spiritual reality as the fellowship of all genuine believers, the church is invisible. This is because we cannot see the spiritual condition of people’s hearts. We can see those who outwardly attend the church, and we can see outward evidences of inward spiritual change, but we cannot actually see into people’s hearts and view their spiritual state—only God can do that. This is why Paul says, “The Lord knows those who are his” (2 Tim. 2:19). Even in our own churches and our own neighborhoods, only God knows who are true believers with certainty and without error.
The visible church throughout the world will always include some unbelievers, and individual congregations will usually include some unbelievers, because we cannot see hearts as God sees them.