A good church is recognized not by its size or antiquity, but by the presence of the marks of the true Church: the faithful preaching of the gospel, the right administration of Christ's ordinances, and the exercise of biblical discipline. These marks serve to distinguish the true Church from the false, as it centers its life on Christ as the only Head.
To identify a faithful congregation, we must look for the marks established by the Word of God rather than human standards of success. As stated in the Belgic Confession Art. 29, the true Church is known where the pure doctrine of the gospel is preached, the sacraments are administered as Christ instituted them, and discipline is exercised to preserve the purity of the body. The Scots Confession Ch. XVIII concurs, noting that these signs are more important than antiquity, titles, or numbers. As John Calvin writes in the Institutes 4.1.9, 'Wherever we see the word of God sincerely preached and heard, wherever we see the sacraments administered according to the institution of Christ, there we cannot have any doubt that the Church of God has some existence.'
A church is not a building or an institution of men, but a gathering of those who have been rescued by the grace of God. Because we are all sinful, no church on earth will be perfect; yet, a healthy church will be one that points you to your need for Christ and His finished work. The 1689 LBCF Ch.26 §12 reminds us that believers are bound to join themselves to particular churches where they can receive the benefits of the gospel and submit to the government of Christ. We are to be part of a community that spurs us on toward grace, as the Scripture says: 'and let us consider one another to provoke unto love and good works; not forsaking our own assembling together, as the custom of some is, but exhorting one another; and so much the more, as ye see the day drawing nigh' (Hebrews 10:24-25).