Whilst preparing, I came across this great quote from Fee’s NICNT volume on 1 Corinthians.
The Corinthian error is an easy one to repeat. Not only do we all have normal tendencies to turn natural preferences into exclusive ones, but in our fallenness we also tend to consider ourselves "wise" enough to inform God through whom he may minister to his people. Our slogans take the form of "I am of the Presbyterians," or "of the Pentecostals," or "of the Roman Catholics." Or they might take ideological forms: "I am of the liberals," or "of the evangelicals," or "of the fundamentalists." And these are also used as weapons: "Oh, he's a fundamentalist, you know." Which means that we no longer need to listen to him, since his ideology has determined his overall value as a spokesman for God. It is hardly possible in a day like ours that one will not have denominational, theological, or ideological preferences. The difficulty lies in allowing that it might really be true that "all things are ours," including those whom we think God would do better to be without. But God is full of surprises; and he may choose to minister to us from the "strangest" of sources, if we were but more truly "in Christ" and therefore free in him to learn and to love.
This does not mean that one should not be discriminating; after all, Paul has no patience for that teaching in Corinth which had abandoned the pure gospel of Christ. But to be "of Christ" is also to be free from the tyrannies of one's own narrowness, free to learn even from those with whom one may disagree.