Quomodo autem revocari ad salutem possunt, quos nemo retinet, populus inpellit?
"How is a man to be recalled unto salvation whom nobody restrains as the crowd carries him away?"
-Seneca's Moral Epistle XLI
As Christians, it seems quite en vogue to embrace "judge not..." and do away entirely with "Are you not to judge those inside [the Church]? God will judge those outside." (1 Cor 5:12-13)
Put another way: Christian churches are terrified at the very idea of "church discipline." Seneca, however, demonstrates to us that such discipline is not only commanded by the Christian God, but such discipline makes rational sense even to a pagan!
Seneca argues in his epistle that individuals are subjected constantly to the communis insania, "the insanity of the community." We certainly can't argue with that. At issue is whether or not the Christian Church has an obligation to rescue them from being carried away by this insanity. Well, we seem to answer, of course we have an obligation - so long as it doesn't require us to offend our notion of "God as unconditional love."
Here we find a rational, non-Christian refutation of such a view: love restrains. A love that refuses to restrain someone from being carried away by the crowd when it is necessary is no love at all. Such a love is like a parent that allows their child to jump into the fire because the child wants to do it - this is not loving at all, but rather negligent!
Christians value love that is self-sacrificial and giving. Does it offend your sensibilities to restrain the erring brother or sister? Does discipline and rebuke bother you? In this case you have an opportunity to be faithful, sacrifice your own faulty notion of love, and embrace a difficult path of restraint for the salvation of another from error. The alternative is to be unfaithful, self-loving, and stand idly by while another is carried away by the communis insania.
Thank God He is willing to discipline and restrain us!
"For the moment all discipline seems painful rather than pleasant, but later it yields the peaceful fruit of righteousness to those who have been trained by it." Hebrews 12:11 (ESV)
Seneca's writings are available from Harvard University Press' Loeb Classical Library: http://www.hup.harvard.edu/loeb/