I don't understand what's baffling in this. Modern Yogis of India starting with Ramakrishna Paramahamsa, Swami Vivekananda to Paramahamsa Yogananda, Swami Rama, Shri M, Sadhguru etc. have all considered Jesus as an enlightened master and a manifestation of divinity.
I have heard people saying the stories of Ramakrshna Paramahamsa practising Christianity is made up. I honestly don't know, but I guess there are many books published by Ramakrishna Ashrama itself which says these.
Also if anyone is an authority of Ramakrishna mission it's Swami Vivekananda. Please read the following and then decide yourself what Swamiji's opinion of Christ was.
Jesus Christ was God — the Personal God become man. He has manifested
Himself many times in different forms and these alone are what you can
worship. God in His absolute nature is not to be worshipped.
Worshipping such God would be nonsense. We have to worship Jesus
Christ, the human manifestation, as God. You cannot worship anything
higher than the manifestation of God. The sooner you give up the
worship of God separate from Christ, the better for you [Source]
If I, as an Oriental have to worship Jesus of Nazareth, there is only
one way, that is, to worship him as God and nothing else. [Source]
Everything is the living God, the living Christ; see it as such.
Father is the existence out of which everything comes; Son is that
knowledge. It is in Christ that God will be manifest. God was
everywhere, in all beings, before Christ; but in Christ we became
conscious of Him. This is God. The third is bliss, the Holy Spirit [Source]
Had I lived in Palestine, in the days of Jesus of Nazareth, I would
have washed his feet, not with my tears, but with my heart’s
I have come to deal with principles. I have only to preach that God
comes again and again, and that He came in India as Krishna, Rama, and
Buddha, and that He will come again. It can almost be demonstrated
that after each 500 years the world sinks, and a tremendous spiritual
wave comes, and on the top of the wave is a Christ.Source
In the last saying you can clearly see him comparing Jesus with Rama and Krishna and Buddha. Many Hindu Atheists question that why all the incarnations of God happen only in India. And when Krishna promised he will take birth whenever adharma increases, did he say it applies to only India?
No. But many people say Bharata is karma bhoomi so the incarnation happens only in India.
One can agree that most incarnations of God happen in India but to hold no incarnation of God happens outside India is simply going against the idea of Krishna in Gita. What will happen if Adharma increases in foreign lands? Ramakrishna mission people and many yogis believe that Jesus was one such incarnation of the divine.