What the Bible says about church unity and purity

John 17:20-23

Not for these only do I pray, but for those also who will believe in me through their word, that they may all be one; even as you, Father, are in me, and I in you, that they also may be one in us; that the world may believe that you sent me. The glory which you have given me, I have given to them; that they may be one, even as we are one; I in them, and you in me, that they may be perfected into one; that the world may know that you sent me, and loved them, even as you loved me.

Ephesians 4:1-6

I therefore, the prisoner in the Lord, beg you to walk worthily of the calling with which you were called, with all lowliness and humility, with patience, bearing with one another in love; being eager to keep the unity of the Spirit in the bond of peace. There is one body, and one Spirit, even as you also were called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all, who is over all, and through all, and in us all.

1 Corinthians 5:1-13

It is actually reported that there is sexual immorality among you, and such sexual immorality as is not even named among the Gentiles, that one has his father’s wife. You are puffed up, and didn’t rather mourn, that he who had done this deed might be removed from among you. For I most certainly, as being absent in body but present in spirit, have already, as though I were present, judged him who has done this thing. In the name of our Lord Jesus Christ, you being gathered together, and my spirit, with the power of our Lord Jesus Christ, are to deliver such a one to Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus. Your boasting is not good. Don’t you know that a little yeast leavens the whole lump? Purge out the old yeast, that you may be a new lump, even as you are unleavened. For indeed Christ, our Passover, has been sacrificed in our place. Therefore let us keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth. I wrote to you in my letter to have no company with sexual sinners; yet not at all meaning with the sexual sinners of this world, or with the covetous and extortionists, or with idolaters; for then you would have to leave the world. But as it is, I wrote to you not to associate with anyone who is called a brother who is a sexual sinner, or covetous, or an idolater, or a slanderer, or a drunkard, or an extortionist. Don’t even eat with such a person. For what do I have to do with also judging those who are outside? Don’t you judge those who are within? But those who are outside, God judges. “Put away the wicked man from among yourselves.”

2 Corinthians 6:14-18

Don’t be unequally yoked with unbelievers, for what fellowship have righteousness and iniquity? Or what fellowship has light with darkness? What agreement has Christ with Belial? Or what portion has a believer with an unbeliever? What agreement has a temple of God with idols? For you are a temple of the living God. Even as God said, “I will dwell in them, and walk in them; and I will be their God, and they will be my people.” Therefore “‘Come out from among them, and be separate,’ says the Lord. ‘Touch no unclean thing. I will receive you. I will be to you a Father. You will be to me sons and daughters,’ says the Lord Almighty.”

Titus 3:9-11

but shun foolish questionings, genealogies, strife, and disputes about the law; for they are unprofitable and vain. Avoid a factious man after a first and second warning, knowing that such a one is perverted and sins, being self-condemned.

Romans 16:17-18

Now I beg you, brothers, look out for those who are causing the divisions and occasions of stumbling, contrary to the doctrine which you learned, and turn away from them. For those who are such don’t serve our Lord, Jesus Christ, but their own belly; and by their smooth and flattering speech, they deceive the hearts of the innocent.

1 Thessalonians 5:12-13

But we beg you, brothers, to know those who labor among you, and are over you in the Lord, and admonish you, and to respect and honor them in love for their work’s sake. Be at peace among yourselves.

Hebrews 12:14-15

Follow after peace with all men, and the sanctification without which no man will see the Lord, looking carefully lest there be any man who falls short of the grace of God; lest any root of bitterness springing up trouble you, and many be defiled by it;

1 Peter 3:8-12

Finally, be all like-minded, compassionate, loving as brothers, tender hearted, courteous, not rendering evil for evil, or insult for insult; but instead blessing; knowing that to this were you called, that you may inherit a blessing. For, “He who would love life, and see good days, let him keep his tongue from evil, and his lips from speaking deceit. Let him turn away from evil, and do good. Let him seek peace, and pursue it. For the eyes of the Lord are on the righteous, and his ears open to their prayer; but the face of the Lord is against those who do evil.”