I certainly can't agree with that statement although I wish it were true.there is the same underlying affirmation in all orthodox Christian denominations surrounding the nature of God, Christ, humanity, sin and forgiveness.
I am one that thinks denominationalism was exactly what Jesus did not want to occur. I believe He wanted us to be one in a much greater sense than the route man took. We are so geared to our rights to be individuals and quite intolerant of other believers that we seek out groups that are closest to the way we think rather than working together to keep Christianity and the true church as being an obvious, distinct, collection of people who are not of this world but belong to another Kingdom and love one another despite certain differences in understandings. Paul tried to put down denominationalism upstarts in the early church but somehow man just had to make someone else the head of the church and not Christ. Much about denominationalism, IMO, comes from man's ego problem and there is a lot of Phariseeism embedded in the dictinctions that believers have made between themselves. There is a joke we probably all have heard about the two guys on a bridge that discussed their similar beliefs and finally when they reached a point of difference, the one shoved the other off the bridge. I think too many denominationally minded people have done something similar and have taken pride in their denomination, some as an idol, to the extent where they look down their nose at believers in other denominations. I really wonder what Jesus thinks of denominationalism ?
But I'm not sure either what Katabole means exactly by not keeping the Word. We all have varying beliefs don't we about what this means ? How does this keep unity if we can't agree on what keeping the Word means ? I think Paul was referring more to keeping Christ as the head of the church and in this regard I think denominations grew to the thousands they are today because they did not keep the Christ of scriptures as the head. When Christ is the head, oneness becomes a reality amongst those born again. When man becomes the head, divisions arise.