Faith

. . . faith is an endowment from the Higher Kingdom and changes all beliefs into an aliveness in the spirit. The quickening of the soul renews the atoms of the body to the very marrow of the bone . . . The capacity for response to sorrows . . . has been heightened greatly.

Bahá’u’lláh, Kitab-i-Iqan, p. vi.

Blessed is the man that hath acknowledged his belief in God and in His signs, and recognized that "He shall not be asked of His doings." Such a recognition hath been made by God the ornament of every belief, and its very foundation. Upon it must depend the acceptance of every goodly deed.  Fasten your eyes upon it, that haply the whisperings of the rebellious may not cause you to slip.

Bahá’u’lláh, Gleanings from the Writings of Bahá’u’lláh, p. 86-87

If thy faith be fearful, seize thou My Tablet, and preserve it in the bosom of trust.

Bahá’u’lláh, Epistle to the Son of the Wolf, p. 103

None have believed in Him except them who, through the power of the Lord of Names, have shattered the idols of their vain imaginings and corrupt desires and entered the city of certitude. The seal of the choice Wine of His Revelation hath, in this Day and in His Name, the Self-Sufficing, been broken. Its grace is being poured out upon men. Fill thy cup, and drink in, in His Name, the Most Holy, the All-Praised.

Bahá’u’lláh, Gleanings from the Writings of Bahá’u’lláh, p. 12

Not until thou hast grasped the mysteries concealed in that which We shall relate unto thee canst thou hope to attain to the stations of faith and certitude in the Cause of God and in those who are the Manifestations of His Cause, the Daysprings of His Command, the Treasuries of His revelation, and the Repositories of His knowledge. Shouldst thou fail in this, thou wouldst be numbered with them that have not striven for the Cause of God, nor inhaled the fragrance of faith from the raiment of certitude, nor scaled the heights of the divine unity, nor yet recognized the stations of divine singleness within the Embodiments of praise and the Essences of sanctity.

Bahá’u’lláh, Gems of Divine Mysteries, p. 5

Regard thou faith as a tree. Its fruits, leaves, boughs and branches are, and have ever been, trustworthiness, truthfulness, uprightness and forbearance.

Bahá’u’lláh, The Compilation of Compilations vol II, p. 327