There is a funny misunderstanding even amongst the God seekers of Christianity who are so educated, that Sanathana Dharma is the private property of Indians and Hindus who seek liberation. But the term Hinduism actually came into use only after the 'coming' of the other so called 'religions'. Needless to say, imposing a name on a religion is wrong in the correct standpoint, and what is more, even the word 'religion' itself is unnecessary if the purpose of what we call religion is served. In fact, this is the exact essence of Sanathana Dharma, which many neglect to understand.
So Hinduism is a meaningless name imposed on Sanathana culture. Of course, divine avatars such as Krishna took birth in India. But godliness will manifest as avatars anywhere in the world when needed. Christ, Mohammed, Zoroaster, etc. fall in that category, which is other than Indian. However, Sanathana Dharma does not want to exclude them as alien. The great messiahs of Sanathana culture like Swami Vivekananda, Swami Ramathirtha, Yogananda Paramahansa, who represent the present form of total godliness, agreed with this statement, rather they even emphasised it. Shirdi Sai Baba was a proof of that even, in his life. Shri Ramakrishna also realized Christianity and Mohammedanism by his austerity in spite of his brahminhood and avatarhood.
Ramkrishna himself suffered pains and sufferings like Christ as a message of sacrifice to the world. He had the same childlike heart of Christ. The case is the same with Swami Sivananda. He also gave the same message of love and sacrifice of Christ and taught the world to attain divinity by annihilating ego on the sacrificial cross of Christ not only on Christmas day, but at every moment.