The Baha'i Faith offers a variety goals, values, requirements, and prohibitions that influence and direct the behavior of followers. Baha'u'llah himself, a Manifestation of God whose word is considered infallible, dictated prohibitions against the following things related to marriage and sexuality:
Homosexual ActivityLike traditional Judaism, Christianity, and Islam, the Baha'i Faith officially forbids homosexual relationships. However, love without sexual expression between people of the same gender is allowed.
One of the reasons for condemnation of homosexuality is that the Baha'i faith considers marriage to be between a man and a woman, and all sex outside of marriage to be adulterous. They do not urge mistreatment or hatred toward homosexuals, which would violate other Baha'i prohibition, nor do they see homosexuality are more-notably sinful than other errors one might commit.
PolygamyThere are passages in Baha'u'llah's Kitab-i-Aqdas that suggest that two wives are permitted in the Baha'i Faith. However, Baha'u'llah also stated that monogamy brings tranquility to a marriage, and that plurality should be conditional upon justice. Abdu'l-Baha, recognized as a legitimate interpreter of Baha'u'llah's words, concluded that all marriages should be monogamous, as one cannot justly care for more than one wife, and that is the official position of Baha'is today.
"Know thou that polygamy is not permitted under the law of God, for contentment with one wife hath been clearly stipulated. Taking a second wife is made dependent upon equity and justice being upheld between the two wives, under all conditions. However, observance of justice and equity towards two wives is utterly impossible. The fact that bigamy has been made dependent upon an impossible condition is clear proof of its absolute prohibition. Therefore it is not permissible for a man to have more than one wife." (Notes from the Kitab-i-Aqdas)
Baha'i are encouraged to be married and have children. However, neither action is required.
AdulteryAll sexual relations outside of marriage are forbidden.