One of the secrets of the believers’ success is the warm brotherhood and solidarity among them. The Qur'an emphasizes the importance of unity: “Truly, Allah loves those who fight in His Cause in battle array as if they were a solid cemented structure.” (Surat as-Saff, 61:4)
Any statement or behaviour that may damage this close brotherhood would be an adversary act against religion itself. Allah warns the believers against this threat in the Qur'an:
“Obey Allah and His Messenger; and fall into no disputes, lest you lose heart and your power depart; and be patient and persevering: for Allah is with those who patiently persevere.” (Surat al-Anfal, 8:46)
Hence, the sincere believer must be extremely cautious of entering into such disputes, avoiding words or manners that may hurt his brothers. Moreover, he should behave in such as way as to increase affection and confidence among them. In the Qur’an, we have the clear decree:
“Say to My servants that they should only say those things that are best: for Satan sows dissensions among them: Satan is to man an avowed enemy.” (Surat al-Isra, 17:53)
If a believer does not have the same opinion as his brother on some issue, he should nevertheless behave and talk in the most modest and humble way. Sharing ideas should remain on the basis of “consultation” and not “debate”. If a contention is observed among two other believers, then what one should do is indicated in the verse below:
“The believers are but a single Brotherhood. So make peace and reconciliation between your two (contending) brothers; and fear Allah, so that you may receive His Mercy.” (Surat al-Hujraat, 49:10)
It should be noted that even a minor argument of any kind may have very negative effects on the Cause.
TAKEN FROM "THE MORAL VALUES OF THE QUR'AN"
BY HARUN YAHYA, GOODWORD PRESS, INDIA, 1999