Briefly stated the Bahá'í conception of sex is based on the
belief that chastity should be strictly practiced by both sexes, not only
because it is in itself highly commendable ethically, but also due to its being
the only way to a happy and successful marital life. Sex relationships of any
form, outside marriage, are not permissible therefore, and whoso violates this
rule will not only be responsible to God, but will incur the necessary
punishment from society.
(From a letter dated 5 September 1938 written on
behalf of Shoghi Effendi to an individual believer; The Compilation of
Compilations, vol. I, A Chase and Holy Life)