And let the peace of God rule in your hearts, to the which also ye are called in one body; and be ye thankful. – Colossians 3:15
The Greek said, “The Hellenes are a race of heroes; remember Sparta and Athens. Are we not foremost in civilisation, and were we not chief in war? Who set bounds to the Persian tyrant, and bade the boastful monarch bite the dust? We hold our heads erect when we think of Marathon and Salamis.” But when the Greek joined the Christian church, he forgot his national boastings, and henceforth gloried only in the cross of Him whose single arm defeated the hosts of Satan, and led captivity captive. The Jew when despised returned scorn for scorn, and said to Greek and Roman, “You may speak of Marathon, but I sing of the Red Sea; you may boast of Persia broken, but I tell of Egypt vanquished, mine are the glories of the Lord of hosts in the far off ages. We were a people when you were as yet unknown, and we are the chosen favourites of Jehovah.” The moment the Jew sat down at the gospel supper, he laid aside his hereditary pride and bigotry, and recognised the fact that the Greek was as much a brother as the believing Hebrew at his side. So the Sythian, when he came into the Christian church, was no longer a Barbarian; he spoke the language of Canaan as correctly as his Grecian fellow Christian. The slave no sooner breathed the air of the Christian church than his shackles fell from him. He might be a slave at home with his master, but he was no slave there. While the freeman, though he had been born free, or with a great price had obtained his freedom, never in the Christian church looked down upon the slave. Bond and free were one in Christ Jesus. Nobody had any personal ground for glory; neither race, nor pedigree, nor rank, nor position, were of any account, but Christ was all. “Christianus sum, I am a Christian,” was and is the universal glorying of all saints.~ C.H. Spurgeon
https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1006.cfm