Do two walk together,
unless they have agreed to meet?
— Amos 3:3
Christians who affirm the normative, traditional, historical, orthodox view of the Bible's teaching on various sins are always accused of being divisive when in sticking to their affirmations they must disassociate with those who don't.
It's a disingenuous claim, however, since unity could have been preserved so long as the agreement did. But when one changes a mind on such matters the division has begun with them (1 Corinthians 1:10), not the one who says, "Ah, you've changed the rules; you've changed the agreement." It would be like the adulterer calling after his wife as she's walking out the door in anger and shame that she's being divisive.
The person who objects is often told they are "singling out" this particular sin as over-important, as more important than unity! But it is not those who protest who are singling out particular sins. It is those bringing the revision, the ones asking, "Did God really say… ?", the ones who suggest it should now be normal what we previously agreed was objectionable who are singling it out, elevating it above the agreement. They are the ones making it the sticking point.
We think of the historical development of credal truth. Many of the historic creeds that so many professing Christians affirm as litmus tests for doctrinal orthodoxy began as responses to introduced heresies. As unbiblical ideas took seed in church communities, those who affirmed orthodoxy thought it best to formulate and codify what had been previously assumed. But it wasn't the crafters of the creeds who were being divisive. It was the heterodox.
And it isn't those who believe the Bible when it says sin is sin that are being divisive; it is those who are introducing the idea that some sins aren't. If you push a decision on something that innovates on the Bible's testimony, you're creating the division. Division begins with that first departure. The first step away from the agreement is the original divide. It is simply necessary, then, for Christians to walk away from a divisive person (Titus 3:10). Perhaps they may even say, "Farewell."
They said to you, "In the last time there will be scoffers, following their own ungodly passions." It is these who cause divisions, worldly people, devoid of the Spirit. – Jude 18-19