One Ummah

Some verses of the Quran that are against division of mankind on a theological, doctrinal and religious basis, of course, Allah has made us diverse but this doesn't mean that we should also make up our own separate religions/sects/denominations based on our own thoughts and whims and then distance ourselves from others who think different, after all, Allah is One, One above all, and tells us to remind to those who are different, to bring everyone together as one Ummah based on Haq.

إِنَّ ٱلَّذِينَ فَرَّقُوا۟ دِينَهُمْ وَكَانُوا۟ شِيَعًا لَّسْتَ مِنْهُمْ فِى شَىْءٍ إِنَّمَآ أَمْرُهُمْ إِلَى ٱللَّـهِ ثُمَّ يُنَبِّئُهُم بِمَا كَانُوا۟ يَفْعَلُونَ

Those who have divided their doctrine and become sects: thou art not of them in anything; their affair is but with God; then will He inform them of what they did.

(6:159)

إِنَّ هَـٰذِهِۦٓ أُمَّتُكُمْ أُمَّةً وَٰحِدَةً وَأَنَا۠ رَبُّكُمْ فَٱعْبُدُونِ ۝ وَتَقَطَّعُوٓا۟ أَمْرَهُم بَيْنَهُمْ كُلٌّ إِلَيْنَا رَٰجِعُونَ ۝

This, your community, is one community, and I am your Lord; so serve Me. But they divided their affair between them; all are returning to Us. (21:92-93)

وَإِنَّ هَـٰذِهِۦٓ أُمَّتُكُمْ أُمَّةً وَٰحِدَةً وَأَنَا۠ رَبُّكُمْ فَٱتَّقُونِ ۝ فَتَقَطَّعُوٓا۟ أَمْرَهُم بَيْنَهُمْ زُبُرًا كُلُّ حِزْبٍۭ بِمَا لَدَيْهِمْ فَرِحُونَ ۝ فَذَرْهُمْ فِى غَمْرَتِهِمْ حَتَّىٰ حِينٍ ۝

And this, your community, is one community, and I am your Lord; so be in prudent fear of Me. But they divided their command among them into writings, each party exulting at what it has, So leave thou them in their flood of ignorance for a time.

(23:52-54)

مُنِيبِينَ إِلَيْهِ وَٱتَّقُوهُ وَأَقِيمُوا۟ ٱلصَّلَوٰةَ وَلَا تَكُونُوا۟ مِنَ ٱلْمُشْرِكِينَ ۝ مِنَ ٱلَّذِينَ فَرَّقُوا۟ دِينَهُمْ وَكَانُوا۟ شِيَعًا كُلُّ حِزْبٍۭ بِمَا لَدَيْهِمْ فَرِحُونَ ۝

Turning in repentance to Him. And be in prudent fear of Him, and uphold the duty; and be not of the idolaters: Of those who divide their doctrine and become sects, each party exulting at what it has.

(30:31-32)

إِنَّمَا ٱلْمُؤْمِنُونَ إِخْوَةٌ فَأَصْلِحُوا۟ بَيْنَ أَخَوَيْكُمْ وَٱتَّقُوا۟ ٱللَّـهَ لَعَلَّكُمْ تُرْحَمُونَ ۝ يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا يَسْخَرْ قَوْمٌ مِّن قَوْمٍ عَسَىٰٓ أَن يَكُونُوا۟ خَيْرًا مِّنْهُمْ وَلَا نِسَآءٌ مِّن نِّسَآءٍ عَسَىٰٓ أَن يَكُنَّ خَيْرًا مِّنْهُنَّ وَلَا تَلْمِزُوٓا۟ أَنفُسَكُمْ وَلَا تَنَابَزُوا۟ بِٱلْأَلْقَـٰبِ بِئْسَ ٱلِٱسْمُ ٱلْفُسُوقُ بَعْدَ ٱلْإِيمَـٰنِ وَمَن لَّمْ يَتُبْ فَأُو۟لَـٰٓئِكَ هُمُ ٱلظَّـٰلِمُونَ ۝

The believers are brethren, so make right between your two brothers; and be in prudent fear of God, that you might obtain mercy. O you who heed warning: let not a people deride another people — it may be that they are better than they; neither women other women — it may be that they are better than they; neither speak ill of yourselves, nor insult one another with nicknames. Bad is the name of perfidy after faith. And whoso turns not in repentance, it is they who are the wrongdoers.

(49:10-11)

وَٱعْتَصِمُوا۟ بِحَبْلِ ٱللَّـهِ جَمِيعًا وَلَا تَفَرَّقُوا۟ وَٱذْكُرُوا۟ نِعْمَتَ ٱللَّـهِ عَلَيْكُمْ إِذْ كُنتُمْ أَعْدَآءً فَأَلَّفَ بَيْنَ قُلُوبِكُمْ فَأَصْبَحْتُم بِنِعْمَتِهِۦٓ إِخْوَٰنًا وَكُنتُمْ عَلَىٰ شَفَا  حُفْرَةٍ مِّنَ ٱلنَّارِ فَأَنقَذَكُم مِّنْهَا كَذَٰلِكَ يُبَيِّنُ ٱللَّـهُ لَكُمْ ءَايَـٰتِهِۦ لَعَلَّكُمْ تَهْتَدُونَ ۝

And hold fast to the rope of God all together, and be not divided. And remember the favour of God upon you: when you were enemies, He united your hearts so that by His favour you became brethren; and you were upon the edge of a pit of fire, and He rescued you from it. Thus does God make plain to you His proofs, that you might be guided.

(3:103)

"Rope of God" i.e. a way out, a treaty, or protection.

May Allah protect us from the Fitnah of Sectarian Hatred.