Accordingly it is not surprising to find that many of the Christian Bedouins were swept into the rushing tide of this great movement and that Arab tribes, who for centuries had professed the Christian religion, now abandoned it to embrace the Muslim faith.

Among these was the tribe of the Banū Ghassān, who held sway over the desert east of Palestine and southern Syria, of whom it was said that they were “Lords in the days of the ignorance and stars in Islam.”^[2]

After the battle of Qādisiyyah (A.H. 14) in which the Persian army under Rustam had been utterly discomfited, many Christians belonging to the Bedouin tribes on both sides of the Euphrates came to the Muslim general and said: “The tribes that at the first embraced Islam were wiser than we. Now that Rustam hath been slain, we will accept the new belief.”^[3]

Similarly, after the conquest of northern Syria, most of the Bedouin tribes, after hesitating a little, joined themselves to the followers of the Prophet.^[4]

That force was not the determining factor in these conversions may be judged from the amicable relations that existed between the Christian and the Muslim Arabs. Muḥammad himself had entered into treaty with several Christian tribes, promising them his protection and guaranteeing them the free exercise of their religion and to their clergy undisturbed enjoyment of their old rights and authority...^[5]

In the battle of the Bridge (A.H. 13) when a disastrous defeat was imminent and the panic-stricken Arabs were hemmed in between the Euphrates and the Persian host, a Christian chief of the Banū Ṭayy sprang forward like another Spurius Lartius to the side of an Arab Horatius, to assist Muthannah the Muslim general in defending the bridge of boats which could alone afford the means of an orderly retreat. When fresh levies were raised to retrieve this disgrace, among the reinforcements that came pouring in from every direction was a Christian tribe of the Banū Namir, who dwelt within the limits of the Byzantine empire, and in the ensuing battle of Buwayb (A.H. 13), just before the final charge of the Arabs that turned the fortune of battle in their favour, Muthannah rode up to the Christian chief and said : "Ye are of one blood with us; come now, and as I charge, charge ye with me.”

The Persians fell back before their furious onslaught, and another great victory was added to the glorious roll of Muslim triumphs. One of the most gallant exploits of the day was performed by a youth belonging to another Christian tribe of the desert, who with his companions, a company of Bedouin horse-dealers, had come up just as the Arab army was being drawn up in battle array. They threw themselves into the fight on the side of their compatriots; and while the conflict was raging most fiercely, this youth, rushing into the centre of the Persians, slew their leader, and leaping on his richly-caparisoned horse, galloped back amidst the plaudits of the Muslim line, crying as he passed in triumph: “I am of the Banū Taghlib. I am he that hath slain the chief.”^[6]

The tribe to which this young man boasted that he be¬longed was one of those that elected to remain Christian, while other tribes of Mesopotamia, such as the Banū Namir and the Banū Quḍā'ah, became Muslim...

From the examples given above of the toleration extended towards the Christian Arabs by the victorious Muslims of the first century of the Hijrah and continued by succeeding generations, we may surely infer that those Christian tribes that did embrace Islam, did so of their own choice and free will.^[7]

The Christian Arabs of the present day, dwelling in the midst of a Muhammadan population, are a living testimony of this toleration... Many of the Arabs of the renowned tribe of the Banū Ghassān, Arabs of the purest blood, who embraced Christianity towards the end of the fourth century, still retain the Christian faith, and since their submission to the Church of Rome, about two centuries ago, employ the Arabic language in their religious services.^[8]