The system of Bahá’í administration

It should be remembered by every follower of the Cause that the system of Bahá’í administration is not an innovation imposed arbitrarily upon the Bahá’ís of the world since the Master’s passing, but derives its authority from the Will and Testament of ‘Abdu’l-Bahá, is specifically prescribed in unnumbered Tablets, and rests in some of its essential features upon the explicit provisions of the Kitáb-i-Aqdas. It thus unifies and correlates the principles separately laid down by Bahá’u’lláh and ‘Abdu’l-Bahá, and is indissolubly bound with the essential verities of the Faith.

 To dissociate the administrative principles of the Cause from the purely spiritual and humanitarian teachings would be tantamount to a mutilation of the body of the Cause, a separation that can only result in the disintegration of its component parts, and the extinction of the Faith itself.

Shoghi Effendi: The World Order of Bahá’u’lláh, P.6

Sayings of the leaders of past religions.

As to thy question regarding the sayings of the leaders of past religions.
Every wise and praiseworthy man will no doubt eschew such vain and profitless talk.

The incomparable Creator hath created all men from one same substance, and hath exalted their reality above the rest of His creatures. Success or failure, gain or loss, must, therefore, depend upon man’s own exertions. The more he striveth, the  greater will be his progress.
We fain would hope that the vernal showers of the bounty of God may cause the flowers of true understanding to spring from the soil of men’s hearts, and may wash them from all earthly defilements.

Gleanings From the Writings of Bahá’u’lláh

The nature of religion.

And now concerning thy question regarding the nature of religion. Know thou that they who are truly wise have likened the world unto the human temple.
As the body of man needeth a garment to clothe it, so the body of mankind must needs be adorned with the mantle of justice and wisdom. Its robe is the Revelation vouchsafed unto it by God. Whenever this robe hath fulfilled its purpose, the Almighty will assuredly renew it. For every age requireth a fresh measure of the light of God. Every Divine Revelation hath been sent down in a manner that befitted the circumstances of the age in which it hath appeared.

Gleanings From the Writings of Bahá’u’lláh, P.82

Process of progressive Revelation

Contemplate with thine inward eye the chain of successive Revelations that hath linked the Manifestation of Adam with that of the Báb. I testify before God that each one of these Manifestations hath been sent down through the operation of the Divine Will and Purpose ...
The measure of the Revelation with which every one of them hath been identified had been definitely fore-ordained. This, verily, is a token of  Our favor unto them, if ye be of those that comprehend this truth….
And when this process of progressive Revelation culminated in the stage at which His peerless, His most sacred, and exalted Countenance was to be unveiled to men’s eyes, He chose to hide His own Self behind a thousand veils, lest profane and mortal eyes discover His glory.

Gleanings From the Writings of Bahá’u’lláh

That the Manifestations of Divine justice,

 "That the Manifestations of Divine justice, the Day Springs of heavenly grace, have when they appeared amongst men always been destitute of all earthly dominion and shorn of the means of worldly ascendancy, should be attributed to this same principle of separation and distinction which animateth the Divine Purpose. Were the Eternal Essence to manifest all that is latent within Him, were He to shine in the plentitude of His glory, none would be found to question His power or repudiate His truth. Nay, all created things would be so dazzled andthunderstruck by the evidences of His light as to be reduced to utter nothingness. How, then, can the godly be differentiated under such circumstances from the froward?
…. It is for this reason that, in every age, when a new Manifestation hath appeared and a fresh revelation of God’s transcendent power was vouchsafed unto men, they that misbelieved in Him, deluded by the appearance of the peerless and everlasting Beauty in the garb of mortal men, have failed to recognize Him.

Gleanings From the Writings of Bahá’u’lláh, P.72