... is not the object of every Revelation to effect a transformation in the whole character of mankind, a transformation that shall manifest itself both outwardly and inwardly, that shall affect both its inner life and external conditions? For if the character of mankind be not changed, the futility of God's universal Manifestations would be apparent. (Bahá'u'lláh, ‘The Kitáb-i-Íqán‘)
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The vitality of men's belief in God is dying out in every land; nothing short of His wholesome medicine can ever restore it. The corrosion of ungodliness is eating into the vitals of human society; what else but the Elixir of His potent Revelation can cleanse and revive it? Is it within human power, O Hakim, to effect in the constituent elements of any of the minute and indivisible particles of matter so complete a transformation as to transmute it into purest gold? Perplexing and difficult as this may appear, the still greater task of converting satanic strength into heavenly power is one that We have been empowered to accomplish. The Force capable of such a transformation transcendeth the potency of the Elixir itself. The Word of God, alone, can claim the distinction of being endowed with the capacity required for so great and far-reaching a change. (Baha'u'llah, ‘Gleanings from the Writings of Baha'u'llah’)
This phenomenal world will not remain in an unchanging condition even for a short while. Second after second it undergoes change and transformation. Every foundation will finally become collapsed; every glory and splendor will at last vanish and disappear, but the Kingdom of God is eternal and the heavenly sovereignty and majesty will stand firm, everlasting. Hence in the estimation of a wise man the mat in the Kingdom of God is preferable to the throne of the government of the world. (‘Abdu’l-Baha, ‘Tablets of the Divine Plan’)
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Christ announced, "That which is born of the flesh is flesh; and that which is born of the Spirit is spirit," meaning that man must be born again. As the babe is born into the light of this physical world, so must the physical and intellectual man be born into the light of the world of Divinity. In the matrix of the mother the unborn child was deprived and unconscious of the world of material existence, but after its birth it beheld the wonders and beauties of a new realm of life and being. In the world of the matrix it was utterly ignorant and unable to conceive of these new conditions, but after its transformation it discovers the radiant sun, trees, flowers and an infinite range of blessings and bounties awaiting it. In the human plane and kingdom man is a captive of nature and ignorant of the divine world until born of the breaths of the Holy Spirit out of physical conditions of limitation and deprivation. Then he beholds the reality of the spiritual realm and Kingdom, realizes the narrow restrictions of the mere human world of existence and becomes conscious of the unlimited and infinite glories of the world of God. Therefore, no matter how man may advance upon the physical and intellectual plane, he is ever in need of the boundless virtues of Divinity, the protection of the Holy Spirit and the face of God. (‘Abdu’l-Baha, From a talk, 27 August 1912, Boston, Massachusetts; ‘The Promulgation of Universal Peace: Talks Delivered by ‘Abdu’l-Bahá during His Visit to the United States and Canada in 1912’)