“an essential preliminary” for those who plan to participate in teaching campaigns

 Those who participate in such a [“teaching”] campaign, whether in an organizing capacity, or as workers to whose care the execution of the task itself has been committed, must, as an essential preliminary to the discharge of their duties,

• thoroughly familiarize themselves with the various aspects of the history and teachings of their Faith.
• In their efforts to achieve this purpose they must study for themselves, conscientiously and painstakingly, the literature of their Faith, delve into its teachings, assimilate its laws and principles, ponder its admonitions, tenets and purposes, commit to memory certain of its exhortations and prayers, master the essentials of its administration, and keep abreast of its current affairs and latest developments.
• They must strive to obtain, from sources that are authoritative and unbiased, a sound knowledge of the history and tenets of Islám—the source and background of their Faith—and approach reverently and with a mind purged from preconceived ideas the study of the Qur’án which, apart from the sacred scriptures of the Bábí and Bahá’í Revelations, constitutes the only Book which can be regarded as an absolutely authenticated Repository of the Word of God.
• They must devote special attention to the investigation of those institutions and circumstances that are directly connected with the origin and birth of their Faith, with the station claimed by its Forerunner, and with the laws revealed by its Author. 

- Shoghi Effendi (‘The Advent of Divine Justice’)

‘Abdu’l-Baha explains how our attitude and behavior should be towards other human beings

O ye Cohorts of God! Praise be to God! —that the Blessed Perfection hath freed the necks from the bonds and fetters and released all from racial attachments by proclaiming, “Ye are all the fruits of one tree and the leaves of one branch.” Be ye kind to the human world, and be ye compassionate to the race of man, deal with the strangers as you deal with the friends, be ye gentle toward the outsiders as you are toward the beloved ones, know the enemy as the friend, look upon the satan as upon the angel, receive the unjust with the utmost love like unto a faithful one, and diffuse far and wide the fragrances of the musk of the gazelles of Kheta and Khotan [1] to the nostrils of the ravenous wolves.

- ‘Abdu’l-Baha (‘Tablets of Abdu’l-Baha’, vol. 1)

[1] Kheta and Khotan are two cities in China celebrated for having large numbers of musk-producing animals. The reference here symbolizes the severed and detached believers who are diffusing the fragrance of the Word of God.

Proofs that Bahá’u’lláh’s “divine Revelation is that same heavenly Kingdom which Christ said was nigh” – ‘Abdu’l-Bahá explains

O thou seeker after Truth! Thy letter was received and thy purpose became known. Thou hast asked: If this divine Revelation is that same heavenly Kingdom which Christ said was nigh, then by what proof and testimony can this be demonstrated, and by what tidings can it be announced? There is no time for a detailed reply, so a brief account is provided.

Know thou that the proofs of the truth of this new Kingdom are the same as those of the Kingdom of Christ. The proof of the subsequent Kingdom is the same as that of the previous one—nay, it is the mightiest proof!

Proofs are of two kinds: those for the common people and those for the learned. The latter will not be convinced by the proofs for the former, who, likewise, will not be assured by the proofs for the latter. The common people seek miracles and marvels, while the learned regard these not as proof; these neither satisfy their search nor quench their thirst. Rather, they seek conclusive rational proofs. Thus, as thou art endowed with a keen vision and a sound mind, we will set forth conclusive and rational proofs that leave none the possibility for denial.

We say that the purpose underlying the advent of the Kingdom is the edification of the souls of men, the progress of the world of humanity, the manifestation of the love of God, the establishment of fellowship and unity amongst all peoples, the appearance of divine perfections, and the realization of the glory of the human race. This is the purpose of the advent of the Kingdom, and this is its result. Observe, then, how the edifying power of Bahá’u’lláh hath enlightened the darksome East, transformed voracious beasts into heavenly angels, endowed the ignorant with knowledge, and caused ravening wolves to become as gazelles in the meads of oneness. Those who, because of custom or belief, rose in enmity against all peoples now associate with all in a spirit of perfect unity. Those who used to burn the Holy Bible out of exceeding ignorance now set forth the truths and mysteries of the Old and New Testaments. In a brief span of time, He so educated His followers that, even in chains and stocks, and under the threat of swords and blades, they would raise the cry of “Yá Bahá’u’l-Abhá!” and would offer sugar candy to their executioners that they might strike the final blow with sweetened mouths. Thou dost surely recall the story of Peter the disciple, and the crowing of the cock!

The incredible, awe-striking power of the Manifestation of God

It is in Our power, should We wish it, to enable a speck of floating dust to generate, in less than the twinkling of an eye, suns of infinite, of unimaginable splendor, to cause a dewdrop to develop into vast and numberless oceans, to infuse into every letter such a force as to empower it to unfold all the knowledge of past and future ages. 

- Baha’u’llah (Quoted by Shoghi Effendi in ‘The Advent of Divine Justice’; The Compilation of Compilations, vol. II, The Power of Divine Assistance)

2017: “the single greatest worldwide opportunity there has ever been for connecting hearts to Bahá’u’lláh”

The signs could hardly be more promising, then, for what the coming year might bring. And what could be more fitting to offer the Blessed Beauty on the two hundredth anniversary of His Birth than the earnest striving of His loved ones to extend the reach of His Faith? The first of the two bicentenaries to be celebrated by the Bahá’í world is thus an occasion with prospects most thrilling. Viewed aright, this year presents the single greatest worldwide opportunity there has ever been for connecting hearts to Bahá’u’lláh. In the months ahead, let all be mindful of this precious chance and alert to the possibilities that exist in every space for acquainting others with His life and sublime mission. 

- The Universal House of Justice (Ridvan 2017 message; Messages from the Universal House of Justice 2001-2022)