Schism in a Christian congregation is not an orderly process, such as one church being born from another with the consent and cooperation of both, or as Christians reorganizing to engage their mission more efficiently and effectively. Orderly separations have occurred throughout Church history without breaking the unity of the body of Christ. In contrast, schism is separation that is non-consensual, bitter, emotionally violent, and steeped in sin. For where jealousy and selfish ambition exist, there will be disorder and every vile practice (James 3:16, ESV). .In both Greek and English schism is an ugly, onomapoetic word suggesting ripping, or tearing asunder. Most English versions of the New Testament have softened it by rendering schisms as "divisions."
A bad call, in my view.. A service club with a difference of opinion in its membership is divided; the living body of Christ torn in two is suffering schism --as far from God's will for the church as can be.
It's hard to generalize about it, because jealousy and selfish ambition aren't the only factors in play; they may not even be present, and when they are they may not be acknowledged. Tolstoy could have been writing about Christian congregations instead of families in the opening sentence of Anna Karenina: "Happy families are all alike; every unhappy family is unhappy in its own way."
So when members of a church in schism ask us to pray for them, we do it, but we are on the spot. We are not part of the quarrel, and we have friends on all sides of it. We pray, but it's tricky. Jesus commands us to pray for the will of God to be done "on earth, as it is in heaven," but since there is no schism in heaven, we cannot pray for a schism to prosper. The only appropriate prayer is for the schism to cease, and the only true way for that to happen is through mutual repentance, forgiveness, and reconciliation. We are to forgive others, not to the degree that they forgive us, but to the degree that God has forgiven all of us. The sternest parable Jesus ever told was about a man who refused to forgive as he had been forgiven. The consequences of his behavior were dire and inevitable. Jesus said, "So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart" (Matthew 18:35).
If the church before the schism was experiencing the unity of the Spirit in the bond of peace—was indeed a church, not a pious social club—its people grieve their loss. If a fragment of the church survives, remains in the building and keeps the name and schedule, it is not the same church it was before. The church is living people, and too many of them are missing.
They are no longer one congregation, but all are still brothers and sisters in Christ. If they persist in treating each other with bitterness, hostility, and/or indifference, however, there will be no unity of the Spirit in the bond of peace among them The poison can even pass from one generation to the next. I have seen it happen. It's like a hereditary disease; "letting it go" doesn't make it go away. Forgetting it doesn't end it: it's more likely to drive it underground, where it thrives in the dark.
Dealing with it here and now requires unconditional repentance and forgiveness—easier to say for an observer than a participant, but still true no matter who says it. Otherwise it remains to be dealt with in the Day when we must all appear before the judgment seat of Christ, so that each one may receive what is due for what he has done in the body, whether good or evil (2 Corinthians 5:10).
Participants in schism repent, forgive, and pray. Observers dare to advise sometimes, and pray. Nobody has an easy time. But if we want what God wants, we will finally walk in the light.
"Eternal God, in whose perfect kingdom no sword is drawn but the sword of righteousness, no strength known but the strength of love: So mightily spread abroad your Spirit, that all peoples may be gathered under the banner of the Prince of Peace, as children of one Father; to whom be dominion and glory, now and for ever. Amen."
--from The Book of Common Prayer