`Abdu’l-Bahá tells us that unity is the single purpose for which all of the Prophets have been sent down to earth:
‘For a single purpose were the Prophets, each and all, sent down to earth; for this was Christ made manifest, for this did Bahá’u’lláh raise up the call of the Lord: that the world of man should become the world of God, this nether realm the Kingdom, this darkness light, this satanic wickedness all the virtues of heaven—and unity, fellowship and love be won for the whole human race, that the organic unity should reappear and the bases of discord be destroyed and life everlasting and grace everlasting become the harvest of mankind.'
Unity is the purpose. The Covenant is the instrument for achieving that purpose. In order to obtain a deeper appreciation of how the Covenant achieves that purpose, it’s helpful to reflect on efforts that people have made in order to subvert the Covenant. To that end, we can turn our attention to the most prominent attempt to create schism among the followers of the Báb.
Shoghi Effendi noted that the Báb never appointed a successor. Rather, the Báb nominated Mírzá Yahyá, Bahá’u’lláh’s half brother, “who would act solely as a figure-head pending the manifestation of the Promised One.” Some 14 years younger than Bahá’u’lláh, Mírzá Yahyá came under His care and protection. Growing up in Bahá’u’lláh’s shadow, Mírzá Yahyá came to both resent and envy the esteem with which Bábís regarded Bahá’u’lláh.
From the days of Bahá’u’lláh’s banishment to Baghdad until His further exile to Adrianople, Mírzá Yahyá, committed a number of deplorable acts too numerous to mention here. For our present purpose, it’s sufficient to note that the fortunes of the Faith of the Báb declined very rapidly due to Mírzá Yahyá’s behavior. Despite the perfidy of Mírzá Yahyá’s behavior, Bahá’u’lláh sought to conceal Mírzá Yahyá’s rebellion. For both Mírzá Yahyá’s sake and to maintain unity among the Bábís, Bahá’u’lláh avoided confrontation and conflict. Despite Bahá’u’lláh’s best efforts to dampen the impact of Mírzá Yahyá’s conduct, the conflict came to a head during the spring of 1866. Mírzá Yahyá orchestrated two attempts on Bahá’u’lláh’s life, disseminated a variety of calumnies regarding Bahá’u’lláh and sowed the seeds of rebellion against the Cause of God.
Though Bahá’u’lláh had publicly declared His Station in Baghdad and the many Tablets that Bahá’u’lláh revealed thereafter, Bahá’u’lláh had yet to formally declare His Station to Mírzá Yahyá. Bahá’u’lláh revealed the Súrih-i-Amr (Súrih of Command), and entrusted it to His amanuensis, Mírzá Áqá Ján, with the instructions that it be delivered to Mírzá Yahyá. He was further instructed to read the Table aloud to Mírzá Yahyá, and demand a conclusive reply. Mírzá Yahyá demurred, saying that he needed a few days of meditation before he could reply. The next day, he sent message to Bahá’u’lláh saying that he received a divine Revelation, and that it was incumbent upon all to obey him. This claim brought about a split between the followers of Bahá’u’lláh and Mírzá Yahyá–a split that Bahá’u’lláh referred to as the “Most Great Separation.”
Bahá’u’lláh changed his residence, and remained sequestered from contact with anyone but His immediate family and closest companions. During this sequestration, Mírzá Yahyá and his confederates sent a number of messages to the believers in Persia, thus announcing his own rebellion to the followers of the Báb. It was at this time that the followers of Bahá’u’lláh became known as Bahá’ís.
The dissension of Mírzá Yahyá and his companions continued until the fall of 1876 when Mírzá Yahyá’s chief henchman, Siyyid Muhammad-í-Isfahaní, promoted the idea of a public confrontation between Mírzá Yahyá and Bahá’u’lláh. This kind of challenge was known in Islam as a Muhábilih, and dates back to the days of Muhammad and His disputation with the unbelievers of Najrán and Medina. Coming face-to-face, it is said, would enable the power of the truth to overcome the falsehoods of the ungodly.
Owing to Bahá’u’lláh’s sequestration and the many times that He had attempted to conceal the ignominious acts of Mírzá Yahyá, neither Siyyid Muhammad nor Mírzá Yahyá ever contemplated the idea that Bahá’u’lláh would accept such a challenge. They mistook Bahá’u’lláh’s mercy and forgiveness as signs of weakness.
Shoghi Effendi gives this account of the situation:
‘A certain Mír Muḥammad, a Bábí of Shíráz, greatly resenting alike the claims and the cowardly seclusion of Mírzá Yaḥyá, succeeded in forcing Siyyid Muḥammad to induce him to meet Bahá’u’lláh face to face, so that a discrimination might be publicly effected between the true and the false. Foolishly assuming that his illustrious Brother would never countenance such a proposition, Mírzá Yaḥyá appointed the mosque of Sulṭán Salím as the place for their encounter. No sooner had Bahá’u’lláh been informed of this arrangement than He set forth, on foot, in the heat of midday, and accompanied by this same Mír Muḥammad, for the afore-mentioned mosque, which was situated in a distant part of the city, reciting, as He walked, through the streets and markets, verses, in a voice and in a manner that greatly astonished those who saw and heard Him.
‘“O Muḥammad!”, are some of the words He uttered on that memorable occasion, as testified by Himself in a Tablet, “He Who is the Spirit hath, verily, issued from His habitation, and with Him have come forth the souls of God’s chosen ones and the realities of His Messengers. Behold, then, the dwellers of the realms on high above Mine head, and all the testimonies of the Prophets in My grasp. Say: Were all the divines, all the wise men, all the kings and rulers on earth to gather together, I, in very truth, would confront them, and would proclaim the verses of God, the Sovereign, the Almighty, the All-Wise. I am He Who feareth no one, though all who are in heaven and all who are on earth rise up against me.… This is Mine hand which God hath turned white for all the worlds to behold. This is My staff; were We to cast it down, it would, of a truth, swallow up all created things.”'
Mír Muḥammad was sent to the mosque to announce Bahá’u’lláh’s impending arrival only to discover that Mírzá Yahyá, claiming the imposition of unforeseen circumstances, would not appear at the confrontation. Hearing this, Bahá’u’lláh returned to His house and revealed a Tablet that gave an account of these events and specified the time of the postponed interview. He fixed His seal to this tablet, and gave it to Nabíl-í-Zarandí. Nabíl, in turn, was instructed to deliver this Tablet to Siyyid Muhammad, and demand, in reply, a similar document from Mírzá Yahyá pledging that the latter’s failure to appear at the tryst would affirm the falsity of his claims. Siyyid Muhammad assiduously avoided even accepting this Tablet.
Shoghi Effendi relates, ‘That undelivered Tablet, Nabíl, recording twenty-three years later this historic episode in his chronicle, affirms was still in his possession, “as fresh as the day on which the Most Great Branch had penned it, and the seal of the Ancient Beauty had sealed and adorned it,” a tangible and irrefutable testimony to Bahá’u’lláh’s established ascendancy over a routed opponent.'
The intense anguish that these events brought to Bahá’u’lláh is accounted in a number of His Tablets. At no point should we think that Bahá’u’lláh viewed His ascendancy over Mírzá Yahyá with any form of pride. Such was Bahá’u’lláh’s love for His brother that He continued to exhort him to set aside his ambitions and return to the Cause.
In the Kitab-í-Aqdás, Bahá’u’lláh affirms:
‘Say: O source of perversion! Abandon thy willful blindness, and speak forth the truth amidst the people. I swear by God that I have wept for thee to see thee following thy selfish passions and renouncing Him Who fashioned thee and brought thee into being… Turn unto Him, and fear not because of thy deeds. He, in truth, forgiveth whomsoever He desireth as a bounty on His part; no God is there but Him, the Ever-Forgiving, the All-Bounteous. We admonish thee solely for the sake of God. Shouldst thou accept this counsel, thou wilt have acted to thine own behoof; and shouldst thou reject it, thy Lord, verily, can well dispense with thee, and with all those who, in manifest delusion, have followed thee.'
On the day that Bahá’u’lláh was banished to `Akká, Mírzá Yahyá was banished to the island of Cyprus. Unable to convince a single resident of that island to join his ranks, Mírzá Yahyá spent the remainder of his days as a pensioner of the Ottoman and later British governments. Denied even British citizenship, Mírzá Yahyá eventually passed away in 1912 having witnessed the extent to which all of his efforts had come to naught.
`Abdu’l-Bahá compares God’s Covenant to the ocean. The Covenant casts ashore those who seek to violate it as if they are foam on the surface of the ocean. While storms and tempests may perturb the ocean’s surface, in its depths the ocean carries on unabated.
‘Say: God sufficeth all things above all things, and nothing in the heavens or in the earth but God sufficeth. Verily, He is in Himself the Knower, the Sustainer, the Omnipotent.'
 `Abdu’l-Bahá, “Selections from the Writings of `Abdu’l-Bahá, p31 (http://www.bahai.org/r/646280805)
 Shoghi Effendi, “God Passes By”, pp 28-9 (http://www.bahai.org/r/628301329)
 Ibid, pp 168-9, (http://www.bahai.org/r/978180645)
 Ibid, p 169, (http://www.bahai.org/r/978180645)
 Bahá’u’lláh, The Kitab-í-Aqdás, paragraph 184 (http://www.bahai.org/r/487734557)
 `Abdu’l-Bahá, “Selections from the Writings of `Abdu’l-Bahá, pp 210-1 (http://www.bahai.org/r/738540448)
 The Báb, Bahá’í Prayers (http://www.bahaiprayers.org/assist4.htm)