You say "there are no perfect churches" - but if we read the three chapters you are referring to, you see that God corrects only five of them:
- Ephesus, Pergamos, Thyatira, Sardis and Laodicea. Smyrna and Philadelphia is doing the right thing, and is accepted by God. The five who are corrected, cannot continue with accepting sin, but have to repent. If not - God himself will leave them, and move the candlestick (Rev 2,5). Therefore there is no reason to remain in a church with sin, if you know of an other church with true teaching and with right practice of sacraments. Here is proof, that God corrects these five churches/assemblies:
Ephesus (Rev 2,5):
Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent.
Pergamos (Rev 2,14-16):
But I have a few things against thee, because thou hast there them that hold the doctrine of Balaam, who taught Balac to cast a stumblingblock before the children of Israel, to eat things sacrificed unto idols, and to commit fornication. So hast thou also them that hold the doctrine of the Nicolaitans, which thing I hate. Repent; or else I will come unto thee quickly, and will fight against them with the sword of my mouth.
Thyatira (Rev 2,20-24):
Notwithstanding I have a few things against thee, because thou sufferest that woman Jezebel, which calleth herself a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols. And I gave her space to repent of her fornication; and she repented not. Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds. And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works. But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden.
Sardis (Rev 3,1-4):
And unto the angel of the church in Sardis write; These things saith he that hath the seven Spirits of God, and the seven stars; I know thy works, that thou hast a name that thou livest, and art dead. Be watchful, and strengthen the things which remain, that are ready to die: for I have not found thy works perfect before God. Remember therefore how thou hast received and heard, and hold fast, and repent. If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee. Thou hast a few names even in Sardis which have not defiled their garments; and they shall walk with me in white: for they are worthy.
Laodicea (Rev 3,15-20):
I know thy works, that thou art neither cold nor hot: I would thou wert cold or hot. So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth. Because thou sayest, I am rich, and increased with goods, and have need of nothing; and knowest not that thou art wretched, and miserable, and poor, and blind, and naked: I counsel thee to buy of me gold tried in the fire, that thou mayest be rich; and white raiment, that thou mayest be clothed, and that the shame of thy nakedness do not appear; and anoint thine eyes with eyesalve, that thou mayest see. As many as I love, I rebuke and chasten: be zealous therefore, and repent. Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me.