Which simply demonstrates yet again that you have NO IDEA what you're talking about!
Clearly the Baha'i Faith does indeed have rules, and it's not at all a "do anything" religion. A tiny bit of research on your part should make this abundantly clear.
The minimum requirement is recognition of (and belief in) the status of Baha'u'llah, our Founder.
The short answer?
Exquisiste good taste! 
The more detailed answer?
To spiritually advance both oneself and society in general.
Peace,
Bruce
Wikipedia:
Bahá'u'lláh - Wikipedia, the free encyclopedia
Bahá'u'lláh declared, as the most recent Manifestation of God, that he was the "Promised One" of all religions, fulfilling the
messianic prophecies found in world religions.
[2] He stated that his claims to being several messiahs converging in one person were the symbolic, rather than literal, fulfilment of the messianic and
eschatological prophecies found in the literature of the major religions.
[2] Bahá'u'lláh's eschatological claims constitute six distinctive messianic identifications: from
Judaism, the incarnation of the "Everlasting Father" from the
Yuletide prophecy of Isaiah 9:6, the "Lord of Hosts"; from
Christianity, the "Spirit of Truth" or Comforter predicted by Jesus in his farewell discourse of John 14-17 and the return of
Christ "in the glory of the Father"; from
Zoroastrianism, the return of
Shah Bahram Varjavand, a Zoroastrian messiah predicted in various late
Pahlavi texts; from
Shi'a Islam the return of the Third Imam,
Imam Husayn; from
Sunni Islam, the return of Jesus (
Isa);
[56] and from
Bábism,
He whom God shall make manifest.
[2]
While Bahá'u'lláh did not himself directly claim to be either the
Hindu or
Buddhist messiah, he did so in principle through his writings.
[2] Later, `Abdu'l-Bahá stated that Bahá'u'lláh was the
Kalki avatar, who in the classical Hindu
Vaishnavas tradition is the tenth and final
Avatar (great incarnation) of
Vishnu who will come to end
The Age of Darkness and Destruction.
[2] Bahá'ís also believe that Bahá'u'lláh is the fulfilment of the prophecy of appearance of the
Maitreya Buddha, who is a future Buddha who will eventually appear on earth, achieve complete enlightenment, and teach the pure Dharma.
[57][58] Bahá'ís believe that the prophecy that Maitreya will usher in a new society of tolerance and love has been fulfilled by Bahá'u'lláh's teachings on world peace.
[57] Bahá'u'lláh is believed to be a descendant of a long line of kings in Persia through
Yazdgerd III, the last monarch of the
Sasanian Dynasty;
[6] he also asserted to be a descendant of
Abraham through his third wife
Keturah.
[59]
So ok he was the return of Christ Jesus and all the others that were foretold to be coming by all of the other religions. That is simple enough.
