Why are you so divisive?
It is true we draw clear lines based on God’s word and avoid fellowship or friendship with those on the other side of the lines. We do this because the Bible demands it, and Jesus Christ did it.
Everywhere Jesus went on earth brought division, just as Simeon had prophesied (Luke 2:34-35): “So there was a division among the people because of him” (John 7:43). “And there was a division among them” (John 9:16). “There was a division therefore again among the Jews for these sayings” (John 10:19). “And they were offended in him” (Matt 13:57). We are not ashamed or worried when the same thing occurs to us due to faith and practice of His holy religion.
Rather than avoid this result from His teaching, Jesus declared it was His intention to create such division to prove His true followers from false ones! He declared, “Think not that I am come to send peace on earth: I came not to send peace, but a sword. For I am come to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law. And a man’s foes shall be they of his own household” (Matt 10:34-36).
When it comes to doctrine and practice, the body of teaching and rules for living in the Bible, Jesus taught you are either for Him or against Him – there is no neutral ground (Matt 12:30; Luke 11:23). We stand with Christ, so we are against all false worshippers, no matter their family ties or other relation to us. We believe, “Let God be true, but every man a liar” (Rom 3:4).
It is only this compromising, effeminate, and worldly generation of Christians that cannot grasp this simple subject. All they want is unity and numbers, though there is no Bible mandate for either that involves compromise. If you love God and His things, then you will hate any doctrine or persons opposed to Him and His things (Ps 15:4; 26:3-5; 31:6; 101:3-8; 139:21-22).
God promised to bring heresies in His churches to identify true Christians (I Cor 11:19). When a church does its job by excluding sinners and cursing false teachers, this godly division shows up clearly and quickly (Rom 16:17-18; I Cor 5:9-11; Gal 1:6-9; II Thess 3:6,14; Titus 3:9-10).
Truth and error have nothing in common, and the friends of this world are the enemies of God (Jas 4:4; I Jn 2:15). This division between the righteous and the wicked existed since Cain and Abel (Pr 29:27), and God drowned the world for trying to mix the two family lines (Gen 6:1-3). Christians should not be unequally yoked with unbelievers (II Cor 6:14-18), and they should never consider marrying anyone but another person zealous for the truth (I Cor 7:39; 11:11).
There are also belly worshippers that mind earthly things more than Jesus Christ (Phil 3:18-19). Just as David would not fellowship with such types (Ps 1:1), we choose those keeping God’s commandments for our friends (Ps 119:63; Pr 9:6; 14:7).
Many more scriptures could be provided, but hopefully this answer will satisfy the righteous.
For further study:
Biblical Separation [PDF]