Scriptures say "If it be possible, as much as lies in you, live peaceably with all men." (Romans 12:18) There is a difference in living in "peace" and living in "harmony." Though we have no right to force our beliefs upon another, as Christians, we can never abandon our principles or violate our conscience or contradict the teachings of Christ. These standards will put us out of harmony with the world. Our behavior is sure to bring persecution. It is even a promise: "Yea, and all that will live godly in Christ Jesus shall suffer persecution." (2 Timothy 3:12.) 

Thus we see that we should strive to live at peace, but harmony is impossible. No true Christian can accept the philosophy of man or the doctrine of demons over the word of God. 2 Corinthians 6:14-18 (CSB), “Don't become partners with those who do not believe. For what partnership is there between righteousness and lawlessness? Or what fellowship does light have with darkness? What agreement does Christ have with Belial? Or what does a believer have in common with an unbeliever? And what agreement does the temple of God have with idols? For we are the temple of the living God, as God said: I will dwell and walk among 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; do not touch any unclean thing, and I will welcome you. And I will be a Father to you, and you will be sons and daughters to me, says the Lord Almighty.” 

We can live in peace by not criticizing or faultfinding, showing mercy and kindness, and doing good unto all as we have opportunity. (Galatians 6:10) Christ has sent us into the world to be wise as serpents and harmless as doves. (Matthew 10:16)