6 A voice says, “Call out.” Then he answered, “What shall I call out?” All flesh is grass, and all its loveliness is like the flower of the field. 7 The grass withers, the flower fades, When the breath of the LORD blows upon it; Surely the people are grass. 8 The grass withers, the flower fades, But the word of our God stands forever. 9 Get yourself up on a high mountain, O Zion, bearer of good news, Lift up your voice mightily, O Jerusalem, bearer of good news; Lift it up, do not fear. Say to the cities of Judah, “Here is your God!” Isa. 40:6–9, NASB
We are commanded in God’s Word to be unified in Christ, to love one another in the Lord. We are commanded to stand firm and rebuke false teachers as we warn the brethren as well, but our role is not to cause division. We are not to separate the wheat from the tares, the sheep from the goats. That is not our job at all. That will happen when our Lord returns in judgment. However, that does not mean that we are to be unified with heretics or to call apostates our brothers. No, there is a unity that we are to have as the Body of Christ that is built by the Holy Spirit that He establishes in God’s truth first then as a visible unity which is the eventual fruit of shared submission to the Word of God.