
Some form of coercion was sometimes used in past religions to gain new followers. This is no longer permissible, as Bahá’u’lláh informs us in this passage from the Súriy-i-Haykal (Súrih of the Temple).
Say: We have ordained that our Cause be taught through the power of utterance. Beware lest ye dispute idly with anyone. Whoso ariseth wholly for the sake of his Lord to teach His Cause, the Holy Spirit shall strengthen him and inspire him with that which will illumine the heart of the world, how much more the hearts of those who seek Him. O people of Bahá! Subdue the citadels of men’s hearts with the swords of wisdom and of utterance. They that dispute, as prompted by their desires, are indeed wrapped in a palpable veil. Say: The sword of wisdom is hotter than summer heat, and sharper than blades of steel, if ye do but understand. Draw it forth in My name and through the power of My might, and conquer then with it the cities of the hearts of them that have secluded themselves in the stronghold of their corrupt desires. Thus biddeth you the Pen of the All-Glorious, whilst seated beneath the swords of the wayward.
If ye become aware of a sin committed by another, conceal it, that God may conceal your own sin. He, verily, is the Concealer, the Lord of grace abounding. O ye rich ones on earth! If ye encounter one who is poor, treat him not disdainfully. Reflect upon that whereof ye were created. Every one of you was created of a sorry germ. It behoveth you to observe truthfulness, whereby your temples shall be adorned, your names uplifted, your stations exalted amidst men, and a mighty recompense assured for you before God.
Bahá’u’lláh

The Festival of Ridván is coming later this month, one of the two Most Great Festivals designated by Bahá’u’lláh in the Kitáb-i-Aqdas (the other is the Declaration of the Báb). The Festival of Ridván commemorates Bahá’u’lláh’s declaration of His prophetic mission in the Garden of Ridván in Baghdad during twelve days in April and May 1863. The first, ninth, and twelfth of these days are designated as holy days (April 21, April 29, and May 2). The following words are from a lengthy Tablet by Bahá’u’lláh known as the Súrih-i-Haykal (Súrih of the Temple). This Tablet is revealed in words of power and majesty. This brief passage, which is only a small sample, has God speaking to Bahá’u’lláh, informing Bahá’u’lláh of the power and authority over mankind and the innate knowledge that God has given Him. The “Temple”, as the context makes clear, is Bahá’u’lláh, as God’s appointed Messenger to mankind for this age.
O Living Temple! We, verily, have made Thee a mirror unto the kingdom of names, that Thou mayest be, amidst all mankind, a sign of My sovereignty, a herald unto My presence, a summoner unto My beauty, and a guide unto My straight and perspicuous Path. We have exalted Thy Name among Our servants as a bounty from Our presence. I, verily, am the All-Bountiful, the Ancient of Days. We have, moreover, adorned Thee with the ornament of Our own Self, and have imparted unto Thee Our Word, that Thou mayest ordain in this contingent world whatsoever Thou willest and accomplish whatsoever Thou pleasest. We have destined for Thee all the good of the heavens and of the earth, and decreed that none may attain unto a portion thereof unless he entereth beneath Thy shadow, as bidden by Thy Lord, the All-Knowing, the All-Informed. We have conferred upon Thee the Staff of authority and the Writ of judgement, that Thou mayest test the wisdom of every command. We have caused the oceans of inner meaning and explanation to surge from Thy heart in remembrance of Thy Lord, the God of mercy, that Thou mayest render thanks and praise unto Him and be of those who are truly thankful. We have singled Thee out from amongst all Our creatures, and have appointed Thee as the Manifestation of Our own Self unto all who are in the heavens and on the earth.
Bahá’u’lláh