Over at Pyromaniacs, Frank Turk has offered excellent encouragement to believers to remain in their local churches whenever possible, even when things go sour. Frank, a.k.a. Centurion, joins in with Calvin, who said much the same:
As we too often see the Church of God defaced by much impurity, to prevent us from stumbling at what appears so offensive, a distinction is made between those who are permanent citizens of the Church, and strangers who are mingled among them only for a time. This is undoubtedly a warning highly necessary, in order that when the temple of God happens to be tainted by many impurities, we may not contract such disgust and chagrin as will make us withdraw from it.
By impurities I understand the vices of a corrupt and polluted life. Provided religion continue pure as to doctrine and worship, we must not be so much stumbled at the faults and sins which men commit, as on that account to rend the unity of the Church.
Yet the experience of all ages teaches us how dangerous a temptation it is when we behold the Church of God, which ought to be free from all polluting stains, and to shine in uncorrupted purity, cherishing in her bosom many ungodly hypocrites, or wicked persons. From this the Catharists, Novatians, and Donatists, took occasion in former times to separate themselves from the fellowship of the godly. The Anabaptists, at the present day, renew the same schisms, because it does not seem to them that a church in which vices are tolerated can be a true church.
But Christ, in Matthew 25:32, justly claims it as his own peculiar office to separate the sheep from the goats; and thereby admonishes us, that we must bear with the evils which it is not in our power to correct, until all things become ripe, and the proper season of purging the Church arrive.
At the same time, the faithful are here enjoined, each in his own sphere, to use their endeavors that the Church of God may be purified from the corruptions which still exist within her.
John Calvin: Comments on Psalm 15