I’ve always thought that denominationalism was a dirty word. I still think that. Most often denominationalism relates to grouping within a group, particularly a religious group. Grouping within a group is contrary to Paul’s teaching in 1 Cor 1-3 and is in defiance of Jesus’ prayer that believers be united (John 17).
Contemporary definitions emphasize naming the group, as if giving the group in a group a name is what distinguishes it from the other named groups. Certainly naming the group in a group does that, but denominationalism begins long before that happens.
Denonimationalism doesn’t begin with a sign in front of a building, and taking down the sign is not the cure for denominationalism. Denominationalism begins in the heart and usually is exhibited in other divisive ways before anyone ever thinks of a name or a sign. Denominationalism begins when one Christian decides he or she will have nothing to do with another Christian because of some disagreement. Denominationalism is first seen by in a sneering looking, a harsh word, a refusal of fellowship, an inhospitable act, a move to another pew, or an act of avoidance in a foyer.
Denominational lines were drawn in Corinth according to favorite preachers, convictions regarding food, gifts of the Spirit, and bank account size. They made groups within the group, dividing from the others in their hearts; and they never made up any names or painted any signs. The body of Christ was divided. Denominationalism was in the body of Christ, and Paul’s response was to call them to repent.
You would call me an amillennialist, non-instrumentalist, pro-cooperation, multi-cup, Bible Class Christian. Some call me progressive, some call me liberal. Others would say I’m conservative. Some might say I’m balanced. I believe it's fine to pay a preacher to work in a particular place. I could use fermented or non-fermented grape juice for the communion, and I break off the large loaf instead of picking up a pre-cut piece of the unleavened bread. I think it's fine to eat and play basketball inside a building that the church owns, though it’s probably not a good idea to eat and play at the same time. Christmas parties are fine with me and so are Halloween parties. I preach about the resurrection at Easter, but I don’t celebrate the day any differently than I do any other Sunday. All these things are true about me, but here’s one thing: I’m not going to say you are less of Christian or not a Christian because you are not quite like me in these areas. That would be denominational. As much as in me is, I will keep the unity of the Spirit though the bond of peace. I will agree with you that division between us will not exist. I will seek to be with other Christians what Jesus prayed we would be. That’s Life at Work!