Question: I read on Wikipedia that Christianity copied the idea of a triune God from Hinduism. Is there any truth to this claim?
Response: No, there is no truth to this claim.
Within the Hindu religion, there is a Trimurti, which refers to a relationship between three Hindu deities. According to a Catholic scholar, J. P. Arendzen, who was during the early 1900s a priest of the Catholic Missionary Society, the Trimurti developed after the time of Christianity and has little or nothing in common with the Holy Trinity in Christianity.
In an article, Pagan Trinities, from Catholic.com, Arendzen wrote:
"The Hindu Trimurti is a late speculation; it does not belong to the ancient Indian or Aryan religion. It came about this way. The worshipers of Vishnu and Siva formed two rival sects. In the original Aryan pantheon they were but two lesser deities, but they gradually gained great popularity. Vishnu was a kind, benevolent god, Siva a stormy and destructive god. Either sect would exalt the greatness of its own god to a sort of identification with absolute deity. This absolute deity was first considered as something impersonal, 'Brahma,' but in Vishnu 'absolute thought and goodness' became more clearly personified and worshiped, not as a faint abstraction, but as an individual. Thus Vishnu gives to Brahma personality, and Brahma gives to Vishnu absoluteness and supremacy. In order to include all three names the following doctrine was started. Vishnu, i.e., Brahma as person, appears as Brahma in order to create the world, as Vishnu (a subordinate form of the original Vishnu) in order to preserve the world, and as Siva in order to destroy it. Thus the three principles governing this material universe are personified....
It is obvious to all that this Trimurti has nothing in common with the Christian Trinity. It has, in fact, not even the number three strictly in common, since under the three names, Brahma, Vishnu, Siva, really four realities are pictured, whether we duplicate Brahma, first as the Absolute and then as the personal God in Vishnu, or whether we again duplicate Vishnu as representative of Brahma with Vishnu as the maintainer. Moreover, the three gods, Brahma, Vishnu, and Siva, in no sense stand towards one another as the Three in the Christian Trinity: Father, Son, and Holy Ghost.
There is no 'destroyer' in the Blessed Trinity, and there is no 'Son' in the Hindu Trimurti. In fact, the Trimurti is only a clerical device by which the names of three popular Hindu divinities are attached to the perpetual cosmic process of production, maintenance, and destruction. It is pantheism in the guise of polytheism and never transcends the material, for even Brahma has a body of some sort and is not pure mind or deity."