The things said most confidently by advanced persons to crowded audiences are generally those quite opposite to the fact; it is actually our truisms that are untrue.The (excellent) chapter as a whole discusses the claim that Buddhism in particular has great overlap with Christianity, including another of my favorite quotes:
Students of popular science, like Mr. Blatchford, are always insisting that Christianity and Buddhism are very much alike, especially Buddhism.There isn't much more one would expect of Sanders, of course, as his entire program is half-baked ideas popular among people who don't think things through, delivered in a tone of outrage by a white-haired guy. It is quite as buffoonish as anything Trump says*, but it's a brand that appeals to a different market.
A more interesting question is why the idea continues to appeal, a century after GKC wrote about it. It always flows in the same direction. Some Christians - or people who want to at least retain some Christianity in their journey - like mystical experience, and so get drawn into eastern practices to get some o' that. Mystical experiences are pretty much the same worldwide - either quiet meditative Oneness or ecstatic shared ceremonies. Buddhism gives a nice structure to the former, but there are plenty of westernised versions of contemplation that can give you the same feeling. People seek that kind of experience to get away. They may return to the workaday world refreshed and ready, but it's the getting away part that attracts. Nothing automatically wrong with that. There are Christian versions of it as well - hence the term retreat.
But to make the mystic experience primary, whether in its Buddhist, Native American, or Hindu version is to retreat in a deeper and ultimately worse way. I have seen it in Christian practices as well. It is to increasingly remove oneself from the congregation, which is ultimately to leave the faith. It's getting away from people that draws folks to contemplations about their own personalities and development, and the meaning of everything. Because people are icky and stupid and irritating. They say mean things and act selfishly, even the ones that are fun sometimes. Having friends that you just pal with, plus having independent spiritual experiences is a lot cheaper, really. Easy to see why it attracts.
Except Christians aren't offered that choice.
*Donald and Bernie's platforms are actually pretty similar, just dressed in different clothes.