II. The visible Church, which is also catholic or universal under the Gospel (not confined to one nation, as before under the law), consists of all those throughout the world that profess the true religion; and of their children: and is the kingdom of the Lord Jesus Christ, the house and family of God, out of which there is no ordinary possibility of salvation.
It’s important to make the distinction between leaving a church that you believe is sinning, which strikes your conscience, and not attending a church at all. Leaving a church for another ‘purer’ church, sure. Leaving a true church, one that has the 3 marks that make it a true church for no church is problematic. Even in light of your conscience, to just quit going to church because you feel there are no other churches that align with your beliefs is not an excuse; Unless there are no true churches in your location, just leaving to quit attending altogether is heretical. We know the WCF says that there are ‘less than pure’ churches out there-ones that have not denigrated to even ‘synagogues of satan’ yet. We have the example in the book of revelation in relation to churches with major problems, yet, they remains true churches with lampstands. This must be considered in light of considering leaving your local assembly, especially if you have nowhere else to receive the means of grace.
IV. This catholic Church hath been sometimes more, sometimes less, visible. And particular Churches, which are members thereof, are more or less pure, according as the doctrine of the gospel is taught and embraced, ordinances administered, and public worship performed more or less purely in them.
The following passage in the book of Revelation, telling God’s people to ‘come out from her’, i.e. a church that has had it’s lampstand removed for it’s error are anathematized; It cannot be considered in light of the 7 churches in Revelation that remain true churches nor the erring church in Corinth. Nowehere in the scriptures do we see people leaving their local congregations due to sin-nowhere do we see exhortations to abandon churches for sin.
Rev. 18:1 After these things I saw another angel coming down from heaven, having great authority, and the earth was illuminated with his glory. 2 And he cried mightily with a loud voice, saying, “Babylon the great is fallen, is fallen, and has become a dwelling place of demons, a prison for every foul spirit, and a cage for every unclean and hated bird! 3 For all the nations have drunk of the wine of the wrath of her fornication, the kings of the earth have committed fornication with her, and the merchants of the earth have become rich through the abundance of her luxury.”
Rev. 18:4 And I heard another voice from heaven saying, “Come out of her, my people, lest you share in her sins, and lest you receive of her plagues. 5 For her sins have reached to heaven, and God has remembered her iniquities. 6 Render to her just as she rendered to you, and repay her double according to her works; in the cup which she has mixed, mix double for her. 7 In the measure that she glorified herself and lived luxuriously, in the same measure give her torment and sorrow; for she says in her heart, “I sit as queen, and am no widow, and will not see sorrow.’ 8 Therefore her plagues will come in one day—death and mourning and famine. And she will be utterly burned with fire, for strong is the Lord God who judges her.
Rev. 18:9 “The kings of the earth who committed fornication and lived luxuriously with her will weep and lament for her, when they see the smoke of her burning, 10 standing at a distance for fear of her torment, saying, “Alas, alas, that great city Babylon, that mighty city! For in one hour your judgment has come.’