This kalimah (word) Lā ilāha illā-Allāh (that none has the right to be worshipped except Allāh), if it said with truthfulness and sincerity from the heart, and acted upon in that which it necessitates – outwardly and inwardly – then its effect will indeed be praiseworthy upon both the individual and the society.

So people cannot truly be united except upon the correct concept of īmān (faith) and the correct ʿaqīdah of Tawḥīd, which are both direct implications of Lā ilāha illā-Allāh. One need only consider the condition of the Arabs before and after Islām.

1. Uniting the word of the Muslims: This will result in strengthening the Muslims and assisting them in defeating their enemies – as long as they continue to follow and practice the same single religion, and as long as they adhere to the same single ʿaqīdah (belief). Allāh – the Most High – said:

وَاعْتَصِمُوا بِحَبْلِ اللَّهِ جَمِيعًا وَلَا تَفَرَّقُوا ۚ ‎﴿١٠٣﴾

“And hold fast to the rope of Allāh and do not be divided”
[Āl-ʿImrān, 3:103].

هُوَ الَّذِي أَيَّدَكَ بِنَصْرِهِ وَبِالْمُؤْمِنِينَ ‎﴿٦٢﴾‏ وَأَلَّفَ بَيْنَ قُلُوبِهِمْ ۚ لَوْ أَنفَقْتَ مَا فِي الْأَرْضِ جَمِيعًا مَّا أَلَّفْتَ بَيْنَ قُلُوبِهِمْ وَلَٰكِنَّ اللَّهَ أَلَّفَ بَيْنَهُمْ ۚ إِنَّهُ عَزِيزٌ حَكِيمٌ ‎﴿٦٣﴾‏

“It is He Who has strengthened you with His help and with the Believers, and moreover, He has put love and affection between their hearts. If you were to spend all that is in the earth, then never could you have united their hearts, but Allāh has united them. Indeed He is the all-Mighty, the all-Wise”
[Al-Anfāl, 8:62-63].

And differing in matters of ʿaqīdah (beliefs) is the cause for splitting, disunity and hostility, as Allāh – the Most High – said:

 إِنَّ الَّذِينَ فَرَّقُوا دِينَهُمْ وَكَانُوا شِيَعًا لَّسْتَ مِنْهُمْ فِي شَيْءٍ ۚ ‎﴿١٥٩﴾‏

“Indeed those who split-up their religion and become sects, you have no part with them in the least”
[6:159].

‏فَتَقَطَّعُوا أَمْرَهُم بَيْنَهُمْ زُبُرًا ۖ كُلُّ حِزْبٍ بِمَا لَدَيْهِمْ فَرِحُونَ ‎﴿٥٣﴾‏

“But people have cut off their affair of unity between them and have become sects, each party rejoicing in that which is with itself”
[Al-Muʾminūn, 23:53].

So people cannot truly be united except upon the correct concept of īmān (faith) and the correct ʿaqīdah of tawḥīd, which are both direct implications of Lā ilāha illā-Allāh. One need only consider the conditions of the Arabs before and after Islām.

2. Prevalence of safety and peace in a unified society, which believes in and abides by Lā ilāha illā-Allāh. Since the individuals in such a society will take care in doing only that which Allāh has made ḥalāl (lawful) and abandoning that which Allāh has made ḥarām (unlawful) – acting in accordance with what the ʿaqīdah necessitates upon them. So this will prevent people from enmity, oppression and injustice, whilst directing them towards co-operation, love and deep brotherhood for the sake of Allāh, acting upon His – the Most High’s saying:

إِنَّمَا الْمُؤْمِنُونَ إِخْوَةٌ ‎﴿١٠﴾

“Indeed the Believers are but brothers”
[Al-Ḥujrāt, 49:10].

This is clearly reflected in the life of the Arabs before and after believing in Lā ilāha illā-Allāh. Before Islām, they lived in hostility and insecurity, constantly fighting and killing each other. However, when they embraced Islām all this changed, and the same people lived with each other in peace and an atmosphere of love and brotherhood prevailed, as Allāh – the Most High – said:

مُّحَمَّدٌ رَّسُولُ اللَّهِ ۚ وَالَّذِينَ مَعَهُ أَشِدَّاءُ عَلَى الْكُفَّارِ رُحَمَاءُ بَيْنَهُمْ ۖ‎﴿٢٩﴾‏

“Muḥammad is the Messenger of Allāh, and those who are with him are strong and mighty against the unbelievers and merciful and kind amongst each other”
[Al-Fatḥ, 48:29].

 وَاذْكُرُوا نِعْمَتَ اللَّهِ عَلَيْكُمْ إِذْ كُنتُمْ أَعْدَاءً فَأَلَّفَ بَيْنَ قُلُوبِكُمْ فَأَصْبَحْتُم بِنِعْمَتِهِ إِخْوَانًا ‎﴿١٠٣﴾

“And remember the favour of Allāh upon you; for you were enemies and He joined your hearts in love so that by His grace you became brothers “
[Āl-ʿImrān, 3:103].

3. Achievement of happiness, attainment of the khilāfah (succession of power and authority) in the earth, maintaining purity of the religion and being steadfast against the onslaught of false beliefs and foreign ideologies.

Allāh said:

وَعَدَ اللَّهُ الَّذِينَ آمَنُوا مِنكُمْ وَعَمِلُوا الصَّالِحَاتِ لَيَسْتَخْلِفَنَّهُمْ فِي الْأَرْضِ كَمَا اسْتَخْلَفَ الَّذِينَ مِن قَبْلِهِمْ وَلَيُمَكِّنَنَّ لَهُمْ دِينَهُمُ الَّذِي ارْتَضَىٰ لَهُمْ وَلَيُبَدِّلَنَّهُم مِّن بَعْدِ خَوْفِهِمْ أَمْنًا ۚ يَعْبُدُونَنِي لَا يُشْرِكُونَ بِي شَيْئًا ۚ وَمَن كَفَرَ بَعْدَ ذَٰلِكَ فَأُولَٰئِكَ هُمُ الْفَاسِقُونَ ‎﴿٥٥﴾‏

“Allāh has promised to those among you who truly have īmān (true faith and belief) and act in obedience to Allāh and His Messenger, that he will grant them rulership upon the earth, just as He granted it to those before them, and that He will establish their religion for them and grant them the authority to practice their religion which He chose and ordered them with. And He will certainly change their situation to one of security, after their fear. Providing that they worship and obey Me, not associating anything else in worship with Me. Then, whoever rejects this favour by disobedience to their Lord – then they are the rebellious transgressors”
[Al-Nūr, 24:55].

So Allāh – the Most Perfect – has made the achievement of these lofty goals conditional upon worshipping and obeying Him not associating any partners with Him. And this is the true meaning of Lā ilāha illā-Allāh.