The Kitáb-i-Aqdas - The Most Holy Book
Index term: with unbelievers, under Marriage
k139.
And now consider what hath been revealed in yet another passage, that perchance ye may forsake your own concepts and set your faces towards God, the Lord of being. He [The Báb] hath said: "It is unlawful to enter into marriage save with a believer in the Bayán. Should only one party to a marriage embrace this Cause, his or her possessions will become unlawful to the other, until such time as the latter hath converted. This law, however, will only take effect after the exaltation of the Cause of Him Whom We shall manifest in truth, or of that which hath already been made manifest in justice. Ere this, ye are at liberty to enter into wedlock as ye wish, that haply by this means ye may exalt the Cause of God." Thus hath the Nightingale sung with sweet melody upon the celestial bough, in praise of its Lord, the All-Merciful. Well is it with them that hearken.
q84.
 
Question: Is it permissible for a believer to marry an unbeliever?
Answer: Both taking and giving in marriage are permissible; thus did the Lord decree when He ascended the throne of bounteousness and grace.