The Kitáb-i-Aqdas
Notes
173.It hath been forbidden you to carry arms unless essential   ¶159
Bahá’u’lláh confirms an injunction contained in the Bayán which makes it unlawful to carry arms, unless it is necessary to do so. With regard to circumstances under which the bearing of arms might be “essential” for an individual, ‘Abdu’l-Bahá gives permission to a believer for self-protection in a dangerous environment. Shoghi Effendi in a letter written on his behalf has also indicated that, in an emergency, when there is no legal force at hand to appeal to, a Bahá’í is justified in defending his life. There are a number of other situations in which weapons are needed and can be legitimately used; for instance, in countries where people hunt for their food and clothing, and in such sports as archery, marksmanship, and fencing.
On the societal level, the principle of collective security enunciated by Bahá’u’lláh (see Gleanings from the Writings of Bahá’u’lláh, CXVII) and elaborated by Shoghi Effendi (see the Guardian’s letters in The World Order of Bahá’u’lláh) does not presuppose the abolition of the use of force, but prescribes “a system in which Force is made the servant of Justice,”1 and which provides for the existence of an international peace-keeping force that “will safeguard the organic unity of the whole commonwealth.”2 In the Tablet of Bisharát, Bahá’u’lláh expresses the hope that “weapons of war throughout the world may be converted into instruments of reconstruction and that strife and conflict may be removed from the midst of men.”3
In that same Tablet Bahá’u’lláh stresses the importance of fellowship with the followers of all religions; He also states that “the law of holy war hath been blotted out from the Book.”4
 
1 Shoghi Effendi, World Order of Bahá’u’lláh, p. 204
2 Shoghi Effendi, World Order of Bahá’u’lláh, p. 203
3 Tablets of Bahá’u’lláh : Bisharát, p. 23 (The fifth Glad-Tidings)
4 Tablets of Bahá’u’lláh : Bisharát, p. 21 (The first Glad-Tidings)
Other Related References
Bahá’u’lláh
Epistle to the Son of the Wolf,   p. 25
Tablets of Bahá’u’lláh : Bisharát, p. 28
Summons of the Lord of Hosts : Súriy-i-Haykal,   p. 23
Lights of Guidance
Self-Defense,   p. 117 (398-400)
Shoghi Effendi
World Order of Bahá’u’lláh,   pp. 92, 191-94, 202-206