Chesterton’s point probably is that Buddhists cannot know the Holy Trinity, which dwells inside us and everywhere, but is still separate from our perceiving selves.
A man who put such thought and energy into religion, yet still rejected Christianity, has a soul in grave danger.
There was a Hindu Yogi by the name of Ramakrishna who lived in the early 1800’s. He reached enlightenment following the traditional Hindu spiritual practices.
He then became a Muslim and again reached enlightenment using their spiritual practices.
He then became a Christian, was baptized and took communion and again reached enlightenment.
He stated that all religions are pathways the lay the foundation for a greater spiritual growth or awakening.
He carried two books with him everywhere that he traveled. One was the 14th century book “An Imitation of Christ.” I highly recommend this book, along with the Bible to guide people on their own individual path.