The Kitáb-i-Aqdas - The Most Holy Book
Index term: Harm
k123.
Liberty must, in the end, lead to sedition, whose flames none can quench. Thus warneth you He Who is the Reckoner, the All-Knowing. Know ye that the embodiment of liberty and its symbol is the animal. That which beseemeth man is submission unto such restraints as will protect him from his own ignorance, and guard him against the harm of the mischief-maker. Liberty causeth man to overstep the bounds of propriety, and to infringe on the dignity of his station. It debaseth him to the level of extreme depravity and wickedness.
k155.
Gambling and the use of opium have been forbidden unto you. Eschew them both, O people, and be not of those who transgress. Beware of using any substance that induceth sluggishness and torpor in the human temple and inflicteth harm upon the body. We, verily, desire for you naught save what shall profit you, and to this bear witness all created things, had ye but ears to hear.
n170.
the use of opium . . . any substance that induceth sluggishness and torpor
This prohibition of the use of opium is reiterated by Bahá'u'lláh in the final paragraph of the Kitáb-i-Aqdas. In this connection, Shoghi Effendi stated that one of the requirements for "a chaste and holy life" is "total abstinence . . . from opium, and from similar habit-forming drugs". Heroin, hashish and other derivatives of cannabis such as marijuana, as well as hallucinogenic agents such as LSD, peyote and similar substances, are regarded as falling under this prohibition.
'Abdu'l-Bahá has written:

As to opium, it is foul and accursed. God protect us from the punishment He inflicteth on the user. According to the explicit Text of the Most Holy Book, it is forbidden, and its use is utterly condemned. Reason showeth that smoking opium is a kind of insanity, and experience attesteth that the user is completely cut off from the human kingdom. May God protect all against the perpetration of an act so hideous as this, an act which layeth in ruins the very foundation of what it is to be human, and which causeth the user to be dispossessed for ever and ever. For opium fasteneth on the soul so that the user's conscience dieth, his mind is blotted away, his perceptions are eroded. It turneth the living into the dead. It quencheth the natural heat. No greater harm can be conceived than that which opium inflicteth. Fortunate are they who never even speak the name of it; then think how wretched is the user.
O ye lovers of God! In this, the cycle of Almighty God, violence and force, constraint and oppression, are one and all condemned. It is, however, mandatory that the use of opium be prevented by any means whatsoever, that perchance the human race may be delivered from this most powerful of plagues. And otherwise, woe and misery to whoso falleth short of his duty to his Lord.


In one of His Tablets 'Abdu'l-Bahá has stated concerning opium: "the user, the buyer and the seller are all deprived of the bounty and grace of God".
In yet another Tablet, 'Abdu'l-Bahá has written:

Regarding hashish you have pointed out that some Persians have become habituated to its use. Gracious God! This is the worst of all intoxicants, and its prohibition is explicitly revealed. Its use causeth the disintegration of thought and the complete torpor of the soul. How could anyone seek the fruit of the infernal tree, and by partaking of it, be led to exemplify the qualities of a monster? How could one use this forbidden drug, and thus deprive himself of the blessings of the All-Merciful?
Alcohol consumeth the mind and causeth man to commit acts of absurdity, but this opium, this foul fruit of the infernal tree, and this wicked hashish extinguish the mind, freeze the spirit, petrify the soul, waste the body and leave man frustrated and lost.


It should be noted that the above prohibition against taking certain classes of drugs does not forbid their use when prescribed by qualified physicians as part of a medical treatment.
q94.
 
Question: Concerning mosques, chapels and temples.
Answer: Whatever hath been constructed for the worship of the one true God, such as mosques, chapels and temples, must not be used for any purpose other than the commemoration of His Name. This is an ordinance of God, and he who violateth it is verily of those who have transgressed. No harm attacheth to the builder, for he hath performed his deed for the sake of God, and hath received and will continue to receive his just reward.