Renewal of Religion

Here is quote from Abdu'l-Baha explaining Renewal of Religion:
"The religion of God is one religion, but it must ever be renewed. Moses, for example, was sent forth to man and He established a Law, and the Children of Israel, through that Mosaic Law, were delivered out of their ignorance and came into the light; they were lifted up from their abjectness and attained to a glory that fadeth not. Still, as the long years wore on, that radiance passed by, that splendour set, that bright day turned to night; and once that night grew triply dark, the star of the Messiah dawned, so that again a glory lit the world.
Our meaning is this: the religion of God is one, and it is the educator of humankind, but still, it needs must be made new. When thou dost plant a tree, its height increaseth day by day. It putteth forth blossoms and leaves and luscious fruits. But after a long time, it doth grow old, yielding no fruitage any more. Then doth the Husbandman of Truth take up the seed from that same tree, and plant it in a pure soil; and lo, there standeth the first tree, even as it was before.

Note thou carefully that in this world of being, all things must ever be made new. Look at the material world about thee, see how it hath now been renewed. The thoughts have changed, the ways of life have been revised, the sciences and arts show a new vigour, discoveries and inventions are new, perceptions are new. How then could such a vital power as religion -- the guarantor of mankind's great advances, the very means of attaining everlasting life, the fosterer of infinite excellence, the light of both worlds -- not be made new? This would be incompatible with the grace and loving-kindness of the Lord. Religion, moreover, is not a series of beliefs, a set of customs; religion is the teachings of the Lord God, teachings which constitute the very life of humankind, which urge high thoughts upon the mind, refine the character, and lay the groundwork for man's everlasting honour."
(Selections from the Writings of Abdu'l-Baha)