Religions change and alter

...If religions did not change and alter, there would be no need of renewal. In the beginning the tree was in all its beauty, and full of blossoms and fruits, but at last it became old and entirely fruitless, and it withered and decayed. This is why the True Gardener plants again an incomparable young tree of the same kind and species, which grows and develops day by day, and spreads a wide shadow in the divine garden, and yields admirable fruit. So it is with religions; through the passing of time they change from their original foundation, the truth of the Religion of God entirely departs, and the spirit of it does not stay; heresies appear, and it becomes a body without a soul. That is why it is renewed.

'Abdu'l Bahá, Some Answered Questions, p. 166