NLONG, you've hit the hardest question in the Book here.
We don't quite seem to be able to keep the balance in our minds or able to define the balance between meekness/humility and pride/assumption. We mostly fail at defining these things. We only see them as outward behaviors, rather than as the Bible portrays the people mentioned in the Bible.
That seems to me to be people's largest fear when it comes to any correction in or from The Church. I appreciate that, because I've always been timid by nature and fearful of my own words. I've gone off line 3 times since having a computer for several reasons. I wanted God to work some balance for myself in this area. I needed Him to 'hone' me, so to speak.
Whether any of us will ever be perfectly perfect while in the flesh, is up for debate also, but I think, with much prayer and being open to examination from the Lord, The Word and others, we come to a constant state of "trying our words".
Peter was an Apostle - as we all know and know all about his life and God's hand on him, from the beginning ... and Paul, compared to Peter, could have been looked down upon by Peter, if Peter's spirit wasn't right ... yet, we read here what happened between them ... Gal 2:11 But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.
None of us are Pauls or John the Baptists or Jesus, but these things are written for our instruction.
The humility and meekness has to be solidly formed within the heart ... which means, that 'words' need not always 'sound meek' but the spirit of the person, or inward nature of that person may be more meek than those who always 'try' to sound meek.
True humility is similar to meekness, in that, it is Biblically seldom possessed by those who have not suffered. Look at Moses, etc.. He was the meekest man, but how did he approach Pharoah in the end. Or looking at the prophets.
The Bible stories are endless to prove your point, but the only caution remains 'within' us.
The Lord would just have us to pray and wait on Him, I believe, before we rebuke 'anyone'.
We should wait and see if maybe God Himself would not change a person. Only He can tell you when and show you when you're speaking or acting in your own 'intellect' instead of His Holy Spirit.
If we only used Jesus as our example, we'd do better.
Some see Him as a quiet, sort of passive Man, forgetting much of what is written of what He did and said at the Temple and to the leaders of it.
We can say, "but we're not Jesus." ... but the Word says, to be like Him ... not trusting in ourselves - but operating in the Spirit, as He did while here. He said, "my words and acts are not my own, but My Father in Heaven gives them to me" ... did He not hear The Father when turning tables over and making that whip or when speaking to the "white-washed-sepulchers-brood-of-vipers, etc, etc," ?
If you truly feel the words are "from The Father", then try it ... if they're not ... He's faithful to chasten.
God help us all. amen