Can you comment on 1 Corinthians 11:18–19 regarding unity?
Well that is, as you know, a difficult verse. I tend to take a very practical way of thinking about it. You will recall that our Lord said to his disciples, 'For it is necessary that temptations [in Greek the word means 'stumbling blocks'] come, but woe to the one by whom the temptation comes!' (Matthew 18:7). It is in that sense inevitable in this world that such things will come. The original meaning of the term 'factions' is not merely difference of doctrine, but party spirits that split the church. Perhaps in one sense, because it is a fallen world, that is inevitable and the Epistles are warning that such things will happen in the last days. They will come, professing to be members of the church, but 'having itching ears they will accumulate for themselves teachers to suit their own passions' (2 Timothy 4:3).
But in God's mercy such things can turn out to be of benefit. For example, when you get serious wrong doctrine about the person of Christ and there comes a split, it does in that sense serve to emphasize what is vital to the Christian faith. So John in one of his letters refers to certain individuals:
They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us. (1 John 2:19)
John presumably is speaking of 'us' in the sense of apostles. These were men who were professing teachers in the church—professed, therefore, to be in sympathy with the apostles, but in fact they weren't, and took to teaching doctrines that contradicted the very foundation of apostolic faith. They went out, both doctrinally and then physically. It served to make clear that they were not genuinely of us. That is sometimes very necessary in the church. If you get folks that in the name of Christian theology teach that Christ was mistaken and that Christ was a sinner like everybody else, and deny his bodily resurrection and deny his atoning sacrifice and deny his literal coming again, then if you don't take a stand against it, you are indeed compromising the fundaments of the faith and confusing the world outside as to what Christians stand for. So at that level, yes, and in that sense it is inevitable, it seems to me, that such heresies will come; and they have come in the course of the church.
As Jude put it, there were 'certain people [who] crept in unnoticed' (Jude 4). True believers don't do that. If you're a true believer, you don't need to 'creep in', but some do that and then come up with their permissive morality.
