My studying of the Islamic sects shows me that all sort of corruptions (strange ideas, bizarre personalities, weird theological practices and rituals) have been incorporated in the Islamic teaching which probably renders the claim of Islam being the one true religion astonishing and slightly inaccurate.
Moving on, I was reading about Prisca Theologia
Prisca theologia is the doctrine within the field of comparative religious studies that asserts that a single, true, theology exists, which threads through all religions, and which was given by God to man in antiquity.
However, this idea has been rejected by the people of Enlightenment.
Another related concept is the Perennial Philosophy
Perennialism, is a perspective within the philosophy of religion which views each of the world’s religious traditions as sharing a single, universal truth on which the foundation of all religious knowledge and doctrine has grown
Followers of the Traditional school claim that a variety of authentic spiritual traditions present in the world today share the same origin and are based on the same metaphysical principles, sometimes called Perennial philosophy. The term philosophia perennis first appears in the Renaissance. It is widely associated with Leibniz who in turn owes it to the 16th century theologian Augustinus Steuchius.
This philosophy also exist in some of the religions of the world
This philosophy (Perennial), that most of the spiritual teaching in world's religions share a single universal truth, sounds amazing and fancy but it may not be the truth.
Critics of this idea point to the fact that many of the world's religious traditions are in blatant conflict with one another. Even setting aside the rather obvious conflicts in matters like the age of the Earth (Christians thought it was younger, and Hindus that it was older, than it actually is), there are major contradictions between religions on matters of ethics and philosophy, which would seem to be the areas in which religions ought to be most consistently accurate, if their ideas have any merit. For instance, Christianity teaches that human nature is sinful and that we must avoid allowing that nature to dominate our actions, lest we commit sinful acts. Taoism, by contrast, embraces nature and encourages people to allow their own natures to influence their behavior. Needless to say, they can't both be right.
* Note: References as quoted and linked in the post itself.
