April 22. On this date in 1954 Shoghi Effendi wrote "We as Bahá'ís are not influenced by the categorical assertions of scholars. We believe that what Bahá'u'lláh has revealed and 'Abdu'l-Bahá has written is from God, and divinely inspired; that Bahá'u'lláh is a Manifestation of God, and has access to a knowledge denied to ordinary human beings."

April 22. On this date in 1954 Shoghi Effendi wrote (also here) "We as Bahá'ís are not influenced by the categorical assertions of scholars. We believe that what Bahá'u'lláh has revealed and 'Abdu'l-Bahá has written is from God, and divinely inspired; that Bahá'u'lláh is a Manifestation of God, and has access to a knowledge denied to ordinary human beings."

You speak of the categorical affirmations of Rudolph Steiner in his book regarding certain things commencing with Christ, and that He was the reincarnation of Zoroaster.
We as Bahá'ís are not influenced by the categorical assertions of scholars. We believe that what Bahá'u'lláh has revealed and 'Abdu'l-Bahá has written is from God, and divinely inspired; that Bahá'u'lláh is a Manifestation of God, and has access to a knowledge denied to ordinary human beings.
Therefore he does not see why, in reading these modern philosophical treatises, you should be perturbed in spirit.
Everybody is entitled to their own opinion. If they do not set it forth with conviction, they are failing in their duty to expose their ideas sincerely and graphically; but because they believe something firmly themselves does not in any way imply that what they believe is the truth. Between the truth which comes from God through His Prophets, and the glimmerings, often misunderstood and misinterpreted, of truth which come from the philosophers and thinkers, there is an immense difference. We must never, under any circumstances, confuse the two.
Bahá'u'lláh has said that learning can be the veil between the soul of man and the eternal truth; in other words, between man and the knowledge of God. We have seen that many people who become very advanced in the study of modern physical sciences are led to deny God, and to deny His Prophets. That does not mean that God and the Prophets have not and do not exist. It only means that knowledge has become a veil between their hearts and the light of God.
You ask why the Manifestation of God for this day, in other words, Bahá'u'lláh, has not given all the detailed answers to the theories advanced by occultists, spiritualists and many of the more abstruse philosophers of the present day.
It would be absolutely impossible for anyone to answer all the questions that might be asked by the curious, whether scholars or ordinary people, on any subject. If the Prophet of God only came to this world in order to answer people's questions, and elucidate all the "nonsense", for the most part, that people have gotten together and formed into cults and philosophies, They would have no time to instruct man by Their example and through Their Teachings in a new way of life.
We must turn aside from these vain imaginings and suppositions and philosophizings of the world, and fix our eyes upon the clear stream of the Teachings of Bahá'u'lláh. Out of these Teachings, and the society which they will create on this planet, will come a solution to all of the problems of men. Gradually, greater scholars, more deeply spiritual thinkers, will be able to answer from a Bahá'í standpoint many of these questions. It is not necessary that they should be in the divine text; they can be studied and learned in the future; but at present we have not had time to evolve the Bahá'í scholars who can deal with these subjects in detail, and take upon themselves to answer the abstruse points and the many unfounded doctrines which are advanced by modern philosophers.
The Guardian urges you to turn you mind away from these abstrusities, and devote yourself not only to studying the books at hand in the French language, of our Faith, but also to teaching other people.
It is very unlikely that you will be able either to successfully argue with, or to convert, any of the people who study these topics you have mentioned in your letter. They are more interested in mystical things, and in mystery itself, than in this present world in which we live, and how to solve its problems. They enjoy abstractions and complications. Minds such as these are not going to be able to accept the Revelation of Bahá'u'lláh, which is for here and now, and which involves the purification of the mind, and an application of His teachings to daily life.
He therefore urges you to set aside all of these thoughts from your mind, to turn with a loving and prayerful heart to Bahá'u'lláh, and ask him to guide you daily to souls that are receptive to, and ready to receive, His Message, and not harass yourself anymore with these idle questions, which in the first place, cannot be answered, and in the second place, for the most part do not require an answer, because they are not sufficiently important in themselves.
What Bahá'u'lláh means by the faculty of sight and hearing is the physical faculty, not a spiritual abstraction. He means that we have been given eyes and ears to appreciate what goes on in this world, by Almighty God; in other words, we can read the Teachings and listen to the Message of the Prophet. This is to be taken literally.
We know from His Teachings that Reincarnation does not exist. We come on to this planet once only. Our life here is like the baby in the womb of its mother, which develops in that state what is necessary for its entire life after it is born. The same is true of us. Spiritually we must develop here what we will require for the life after death. In that future life, God, through His mercy, can help us to evolve characteristics which we neglected to develop while we were on this earthly plane. It is not necessary for us to come back and be born into another body in order to advance spiritually and grow closer to God.
This is the Bahá'í Teaching, and this is what the followers of Bahá'u'lláh must accept, regardless of what experiences other people may feel they have. You yourself must surely know that modern psychology has taught that the capacity of the human mind for believing what it imagines is almost infinite. Because people think they have a certain type of experience, think they remember something of a previous life, does not mean they actually had the experience, of existed previously. The power of their mind would be quite sufficient to make them believe firmly such a thing had happened.
We must use the Writings of the Prophets as our measurement. If Bahá'u'lláh had attached the slightest importance to occult experiences, to the seeing of auras, to the hearing of mystic voices; if He had believed that reincarnation was a fact, He, Himself, would have mentioned all of these things in His Teachings. The fact that He passed over them in silence shows that to Him, they had either no importance or no reality, and were consequently not worthy to take up His time as the Divine Educator of the human race.
We must turn our faces away from these things, and toward the actual practice of His Teachings in our every-day life through out Bahá'í Administration, and in our contact with other people and the examples we give.
(From a letter dated 22 April 1954 written on behalf of the Guardian to an individual believer)

Also here...

1820. Bahá'í Position on Reincarnation
"It is clear from the teachings of Bahá'u'lláh about the nature of the soul and of life after death as published in 'Gleanings from the Writings of Bahá'u'lláh', that the Bahá'í position on this subject is wholly incompatible with the theory of reincarnation. We suggest that you refer this friend to the explanation of 'return' as given by Bahá'u'lláh in the Kitab-i-Iqan and the statements made by Abdu'l-Bahá in 'Some Answered Questions'.
"...for your additional information we give the following quotations from letters written on behalf of the beloved Guardian on this subject:
'No revelation from God has ever taught reincarnation; this is a man-made conception. The soul of man comes into being at conception.' (To an individual believer, April 1, 1946)
'The Bahá'í view of 'reincarnation' is essentially different from the Hindu conception. The Bahá'ís believe in the return of the attributes and qualities, but maintain that the essence or the reality of things cannot be made to return. Every being keeps its own individuality, but some of his qualities can be transmitted. The doctrine of metempsychosis upheld by the Hindus is fallacious.' (To an individual believer, March 27, 1938)
'Evolution in the life of the individual starts with the formation of the human embryo and passes through various stages, and even continues after death in another form. The human spirit is capable of infinite development.
'Man's identity or rather his individuality is never lost. His reality as a person remains intact throughout the various states of his development. He does not preexist in any form before coming into this world.' (To an individual believer, November 26, 1939)
'We as Bahá'ís are not influenced by the categorical assertions of scholars. We believe that what Bahá'u'lláh has revealed and Abdu'l-Bahá has written is from God, and divinely inspired; that Bahá'u'lláh is a Manifestation of God, and has access to a knowledge denied to ordinary human beings.'" (Letter written to an individual believer, April 22, 1954 on behalf of the Guardian)
(From a letter of the Universal House of Justice to the National Spiritual Assembly of Monaco, August 5, 1969)