From the days of Adam until today, the religions of God have
been made manifest, one following the other, and each one of them fulfilled its
due function, revived mankind, and provided education and enlightenment. They
freed the people from the darkness of the world of nature and ushered them into
the brightness of the Kingdom. As each succeeding Faith and Law became revealed
it remained for some centuries a richly fruitful tree and to it was committed
the happiness of humankind. However, as the centuries rolled by, it aged, it
flourished no more and put forth no fruit, wherefore was
it then made young again.
The religion of God is one religion, but it must ever be renewed…
(‘Abdu’l-Baha, ‘Selections from the Writings of ‘Abdu’l-Baha’)