To the Western mind Hinduism sounds like a hopeless hodgepodge. It is filled with changes, additions and contradictions. Any attempt to put it into a logical system is like trying to repair a computer blindfold while wearing gloves. But the people of India are comfortable with the complexities of Hinduism because it has grown with them since the beginning of their history. It is deeply embedded in their culture and they wouldn't dream of questioninbg it.
That's the biggest reason Christianity hasn't had much impact on the people of India. There are those, of course, who gladly accept Christ, nut most reject the Gospel because it seems to be too much a part of the alien Western culture.
A few forms of Hinduism have absorbed certain Christian ideas. Vedanta is a good example of this. According to Vedanta, the creator-god Brahman has incarnated himself in human form many times. He will do so again. Christ, Buddha, Krishna and many others are believed to have been incarnations of Brahman, which Hindus call avatars (super-saviours).
The followers of Vedanta believe that the most recent incarnation of Brahma is that of Sri Ramakrishna. Ramakrishna lived in Bengal toward the end of the nineteenth century. His followers say that he practiced all the spiritual disciplines of Hinduism, Christianity and Islam, and that he attained a vision of God in each one. Thus he was able to say: "Truth is one; sages call it by various names." Ramakrishna would often say, "Many faiths are but paths leading to the one reality, God."
Vedanta, then, is friendly with all religions. Aldous Huxley, author if Brave New World and one of Vedanta's ardent followers, said: "It is perfectly possible for people to remain good Christians, Hindus, Buddhists, or Muslims and yet be united in full agreement on the basic doctrines of the Perennial Philosophy."
But what does Vedanta have to say about Yah'shua the Messiah (Jesus Christ)? Swami Prabhavananda says that a Hindu "would find it easy to accept Christ as a divine incarnation and to worship him unreservedly, exactly as he worships Krishna or another avatar (teacher) of his choice. But he cannot accept Christ as the only Son of God." 
 Swami Prabhavananda, The Sermon on the Mount According to Vedanta (Hollywood, CA: Vedanta Press, 1972).