>>I'm beginning to be firmly convinced of the viewpoint (don't remember who put forth this view) that Christianity is simply Buddhism repackaged around Christ.
This point of view is not new, and there are plenty of theories as to how this could have come about - there are quite a number of books by European writers suggesting this: (a) one thread suggesting he picked it up from the Essene sect, which seems to have had some contact with Buddhist monks (perhaps in nearby Egypt); and (b) while others have propagated the idea that Jesus himself came to India and got the ideas from here.
There is no solid evidence for any of this, except some tantalising circumstantial bits and pieces which can suddently concretize into something substantial if even one solid bit of real evidence (say an old text - like the Dead Sea Scrolls) is found again, or if one of the hundreds of thousands of ancient manuscripts in India describe someone identifiable as Jesus Christ.
The broad theory, as it exists, goes like this: In his youth, Jesus was a precocious child, who had something to say, even to the priests in Jewish temples (no one knows if this is actually true, but this is a recurrent theme in mainstream Christianity). The narrative then implies that about the age of 12 he took the ancient overland route to India, via the Khyber presumably, or possibly by sea, and even went to Jagannath in Puri. Undoubtedly, on the way he must have met a vast number of Dharmic gurus, swamis and others who basically proliferated throughout the land at the time.
From them, he picked up a number of key concepts and even some of their behavioural traits (gentleness, a certain detachment, perhaps a sense of quiet authority, etc). Gradually, having picked up all that, he returned home, stewed in the local milieu for about a year and - given the warzone that Judea & Samaria were a the time, not to mention riven with poverty and Roman & Elite injustice - stepped out of Nazareth speaking some of what he had learned during his years in India, largely what seems to the West as "Buddhist" concepts now.
On the other side, it is speculated that he engaged with people of the Essene sect, who were regarded as more zealous and "outre" by the regular Jews and that he may have imbibed some of their supposed "Buddhist" ideas and transmitted them.
It is of course more than a little curious that the Buddha, born over 600 years prior, was also born of a virgin and that the Buddha's mother's name was Maya, which is interchangeable with Maria in Greek (i.e. Mary in the English language bibles). In the Greek bibles, it is still Maria.
As I said, I have read several of these books, listened to innumerable lectures on related subjects, but have not come away convinced in the slightest, even though our own Government of India put this out (in 2007 - when you know who was in power).https://www.youtube.com/watch?v=D9w-xJfSOyc
Jesus in Kashmir, no less! The poor man, if he actually ever existed, is probably the most over-used political tool so much so that the cult which he started and became a global faith is now a blunt instrument, used primarily by crude evangelists and cynical churchmen.
>>The proselytising methods adopted by both religions seem to be exactly the same.
I disagree quite vehemently about this. Buddhism is not an absolutist "my way or the highway to hell" sort of faith system, indeed it is hardly even a faith system. At best it is a form of Spiritual Atheism at heart (even though the Buddha has become deified over time). They debated others, mainly Brahmins, because they were the keepers of the Sanatana Dharma, but not only Brahmins. They took on all comers, as did the Brahmins. Within India, I have yet to hear of a Buddhist army on the march in order to impose its faith on others, where as you have
"Onwards Christian Soldiers, Marching as to War,
Looking Unto Jesus, Who has Gone Before,
Christ the Royal Master, Leads against the Foe,
Onwards into Battle, See his Banners Flow!"
Buddhist proselytization has been of a passive sort, i.e. people spread out and started talking - and it was essentially take it or leave it. The sophistication of its doctrine and the inherent philosophical concepts (bounded firmly by reason) was such that rulers, and then the general public, gradually accepted it over time; and when a more (or equally) substantial line of reasoning (Advaita Vedanta) came to the fore, people who liked their rituals, their daily worship, their visits to the temple and the chants of the Brahmins as well as other services they provided, simply kept on doing it under the Upanishadic rubric, rather than those of the teachings of the Buddha - although many held on to that too, until the Muslim hordes came in and started slaughtering all and sundry. In my personal view, one of the key reasons why Buddhism dissipated within India itself is because Adi Shankara did not prohibit or even proscribe the Brahminical practices, the ordinary folks daily rituals, the worship, and the temple customs.
In the absense of Hinduism outside India, at least not in great societal depth, Buddhism caught on like wildfire and spread to Japan in the East and most probably across the Levantine and North African plans (but in much smaller numbers because of the inhospitable climates and the desert terrain). There was no real challenge to its doctrine. People only had to speak, and eventually, everywhere, the elite will subscribe to the most sophisticated doctrine, i.e. the one with which the can most easily bamboozle the lower rungs of society; and such doctrines, if they have the greatest component of truth in them, eventually are the most useful also. In India, Buddhism was sorted out by Advaitism, which is truly the crest-jewel of refinement in the search for truth.
The rest of the world has had no exposure to Advaitism yet, not in any substantial way. But, it is beginning. Over the last 60 odd years, steadily and slowly numerous gurus have gone out and spoken. The idea is powerful, and fundamental, and vital - and it holds the force of a very close alignment with the sciences (just as Buddhism does). Eventually, it will make its mark on the world. Check out the interest these days for "Non-Dualism" (which is basically Advaita, with the spices reduced so Europeans can consume it). But it is the elite who eat it first. Let them pick this little, dense, unendingly energising morsel of truth from the buffet of philosophical concepts that India has to offer and taste it. Properly. It will enable them to be people of "faith" to the lower-minds among their societies, and it will enable them to think of themselves as "understanders" of the ultimate - better explained than anywhere else, by anyone else. And quite finely cut for the 21st century and beyond.