When their teaching is healthy, but their behaviour isn't

What does it mean to 'contend for the faith once for all delivered to the saints' (Jude 3)?

Here is a clear call to disagree, to argue, to oppose, to speak against, to condemn – but is this only a matter of doctrine?

We know that sound doctrine is indispensable for the health of God’s people. Many fierce and essential battles have been fought over this ground over the last 2,000 years and still are being fought today. But is it enough to look at someone’s doctrine and leave it at that? Are orthodox sermons a guarantee that a church or ministry leader is a true shepherd of the sheep?