"Although the Great Schism occurred in the eleventh century, dealing with schismatic people in the local church has been a problem since the days of the apostles." This problem is the theme of Michael Brown's article in the current issue of Tabletalk. "Schism is a division within or split from a church. It occurs in a congregation or denomination when a faction is formed on the basis of something other than the faith once for all delivered to the saints. It is distinguished from heresy, which is false teaching about doctrine. While heresies can (and often do) lead to schisms, most schisms in the local church do not involve heresy. They usually erupt from some 'quarrel over opinions' (Rom. 14:1) in matters not essential to the faith."
"Although Christians have liberty to differ in their opinions about things such as, say, the age of the earth, healthcare, and the best school for their children, any attempt to base Christian unit y upon such opinions is illegitimate and schismatic. Our consumer preferences, cultural practices, or political convictions do not unite us in the church, and we have no right to divide over them. To do so is an attack upon the unity that the Spirit has given us."
Read Schism and the Local Church to learn about the problems those schismatic people may bring to a church.