"When the greatest part of a Church maketh defection from the Truth, the lesser part remaining sound, the greatest part is the Church of Separatists." - Samuel Rutherford, The Due Right Of Presbyteries, p. 255.
"Divisions and separations are most objectionable in religion. They weaken the cause of true Christianity... But before we blame people for them, we must be careful that we lay the blame where it is deserved. False doctrine and heresy are even worse than schism. If people separate themselves from teaching that is positively false and unscriptural, they ought to be praised rather than reproved. In such cases separation is a virtue and not a sin." - J.C. Ryle.
"Some one will therefore ask me what counsel I would like to give to a believer who thus dwells in some Egypt or Babylon where he may not worship God purely, but is forced by the common practice to accommodate himself to bad things. The first advice would be to leave (i.e., relocate-ed.) if he could... If someone has no way to depart, I would counsel him to consider whether it would be possible for him to abstain from all idolatry in order to preserve himself pure and spotless toward God in both body and soul. Then let him worship Godin private (in his home-ed.), praying him to restore his poor church to its right estate." - John Calvin, Come Out From Among Them, The Anti-Nicodemite Writings of John Calvin, Protestant Heritage Press, A Short Treatise, pp. 93-94.